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2156 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Linus Torvalds
|
2004cef11e |
In the v6.12 scheduler development cycle we had 63 commits from 18 contributors:
- Implement the SCHED_DEADLINE server infrastructure - Daniel Bristot de Oliveira's
last major contribution to the kernel:
"SCHED_DEADLINE servers can help fixing starvation issues of low priority
tasks (e.g., SCHED_OTHER) when higher priority tasks monopolize CPU
cycles. Today we have RT Throttling; DEADLINE servers should be able to
replace and improve that."
(Daniel Bristot de Oliveira, Peter Zijlstra, Joel Fernandes,
Youssef Esmat, Huang Shijie)
- Preparatory changes for sched_ext integration:
- Use set_next_task(.first) where required
- Fix up set_next_task() implementations
- Clean up DL server vs. core sched
- Split up put_prev_task_balance()
- Rework pick_next_task()
- Combine the last put_prev_task() and the first set_next_task()
- Rework dl_server
- Add put_prev_task(.next)
(Peter Zijlstra, with a fix by Tejun Heo)
- Complete the EEVDF transition and refine EEVDF scheduling:
- Implement delayed dequeue
- Allow shorter slices to wakeup-preempt
- Use sched_attr::sched_runtime to set request/slice suggestion
- Document the new feature flags
- Remove unused and duplicate-functionality fields
- Simplify & unify pick_next_task_fair()
- Misc debuggability enhancements
(Peter Zijlstra, with fixes/cleanups by Dietmar Eggemann,
Valentin Schneider and Chuyi Zhou)
- Initialize the vruntime of a new task when it is first enqueued,
resulting in significant decrease in latency of newly woken tasks.
(Zhang Qiao)
- Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
(K Prateek Nayak, Peter Zijlstra)
- Clean up and clarify the usage of Clean up usage of rt_task()
(Qais Yousef)
- Preempt SCHED_IDLE entities in strict cgroup hierarchies
(Tianchen Ding)
- Clarify the documentation of time units for deadline scheduler
parameters. (Christian Loehle)
- Remove the HZ_BW chicken-bit feature flag introduced a year ago,
the original change seems to be working fine.
(Phil Auld)
- Misc fixes and cleanups (Chen Yu, Dan Carpenter, Huang Shijie,
Peilin He, Qais Yousefm and Vincent Guittot)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Implement the SCHED_DEADLINE server infrastructure - Daniel Bristot
de Oliveira's last major contribution to the kernel:
"SCHED_DEADLINE servers can help fixing starvation issues of low
priority tasks (e.g., SCHED_OTHER) when higher priority tasks
monopolize CPU cycles. Today we have RT Throttling; DEADLINE
servers should be able to replace and improve that."
(Daniel Bristot de Oliveira, Peter Zijlstra, Joel Fernandes, Youssef
Esmat, Huang Shijie)
- Preparatory changes for sched_ext integration:
- Use set_next_task(.first) where required
- Fix up set_next_task() implementations
- Clean up DL server vs. core sched
- Split up put_prev_task_balance()
- Rework pick_next_task()
- Combine the last put_prev_task() and the first set_next_task()
- Rework dl_server
- Add put_prev_task(.next)
(Peter Zijlstra, with a fix by Tejun Heo)
- Complete the EEVDF transition and refine EEVDF scheduling:
- Implement delayed dequeue
- Allow shorter slices to wakeup-preempt
- Use sched_attr::sched_runtime to set request/slice suggestion
- Document the new feature flags
- Remove unused and duplicate-functionality fields
- Simplify & unify pick_next_task_fair()
- Misc debuggability enhancements
(Peter Zijlstra, with fixes/cleanups by Dietmar Eggemann, Valentin
Schneider and Chuyi Zhou)
- Initialize the vruntime of a new task when it is first enqueued,
resulting in significant decrease in latency of newly woken tasks
(Zhang Qiao)
- Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
(K Prateek Nayak, Peter Zijlstra)
- Clean up and clarify the usage of Clean up usage of rt_task()
(Qais Yousef)
- Preempt SCHED_IDLE entities in strict cgroup hierarchies
(Tianchen Ding)
- Clarify the documentation of time units for deadline scheduler
parameters (Christian Loehle)
- Remove the HZ_BW chicken-bit feature flag introduced a year ago,
the original change seems to be working fine (Phil Auld)
- Misc fixes and cleanups (Chen Yu, Dan Carpenter, Huang Shijie,
Peilin He, Qais Yousefm and Vincent Guittot)
* tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
sched/cpufreq: Use NSEC_PER_MSEC for deadline task
cpufreq/cppc: Use NSEC_PER_MSEC for deadline task
sched/deadline: Clarify nanoseconds in uapi
sched/deadline: Convert schedtool example to chrt
sched/debug: Fix the runnable tasks output
sched: Fix sched_delayed vs sched_core
kernel/sched: Fix util_est accounting for DELAY_DEQUEUE
kthread: Fix task state in kthread worker if being frozen
sched/pelt: Use rq_clock_task() for hw_pressure
sched/fair: Move effective_cpu_util() and effective_cpu_util() in fair.c
sched/core: Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
sched: Add put_prev_task(.next)
sched: Rework dl_server
sched: Combine the last put_prev_task() and the first set_next_task()
sched: Rework pick_next_task()
sched: Split up put_prev_task_balance()
sched: Clean up DL server vs core sched
sched: Fixup set_next_task() implementations
sched: Use set_next_task(.first) where required
sched/fair: Properly deactivate sched_delayed task upon class change
...
|
||
Hao Ge
|
5e9784e997 |
codetag: debug: mark codetags for poisoned page as empty
When PG_hwpoison pages are freed they are treated differently in
free_pages_prepare() and instead of being released they are isolated.
Page allocation tag counters are decremented at this point since the page
is considered not in use. Later on when such pages are released by
unpoison_memory(), the allocation tag counters will be decremented again
and the following warning gets reported:
[ 113.930443][ T3282] ------------[ cut here ]------------
[ 113.931105][ T3282] alloc_tag was not set
[ 113.931576][ T3282] WARNING: CPU: 2 PID: 3282 at ./include/linux/alloc_tag.h:130 pgalloc_tag_sub.part.66+0x154/0x164
[ 113.932866][ T3282] Modules linked in: hwpoison_inject fuse ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_conntrack ebtable_nat ebtable_broute ip6table_nat ip6table_man4
[ 113.941638][ T3282] CPU: 2 UID: 0 PID: 3282 Comm: madvise11 Kdump: loaded Tainted: G W 6.11.0-rc4-dirty #18
[ 113.943003][ T3282] Tainted: [W]=WARN
[ 113.943453][ T3282] Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
[ 113.944378][ T3282] pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 113.945319][ T3282] pc : pgalloc_tag_sub.part.66+0x154/0x164
[ 113.946016][ T3282] lr : pgalloc_tag_sub.part.66+0x154/0x164
[ 113.946706][ T3282] sp : ffff800087093a10
[ 113.947197][ T3282] x29: ffff800087093a10 x28: ffff0000d7a9d400 x27: ffff80008249f0a0
[ 113.948165][ T3282] x26: 0000000000000000 x25: ffff80008249f2b0 x24: 0000000000000000
[ 113.949134][ T3282] x23: 0000000000000001 x22: 0000000000000001 x21: 0000000000000000
[ 113.950597][ T3282] x20: ffff0000c08fcad8 x19: ffff80008251e000 x18: ffffffffffffffff
[ 113.952207][ T3282] x17: 0000000000000000 x16: 0000000000000000 x15: ffff800081746210
[ 113.953161][ T3282] x14: 0000000000000000 x13: 205d323832335420 x12: 5b5d353031313339
[ 113.954120][ T3282] x11: ffff800087093500 x10: 000000000000005d x9 : 00000000ffffffd0
[ 113.955078][ T3282] x8 : 7f7f7f7f7f7f7f7f x7 : ffff80008236ba90 x6 : c0000000ffff7fff
[ 113.956036][ T3282] x5 : ffff000b34bf4dc8 x4 : ffff8000820aba90 x3 : 0000000000000001
[ 113.956994][ T3282] x2 : ffff800ab320f000 x1 : 841d1e35ac932e00 x0 : 0000000000000000
[ 113.957962][ T3282] Call trace:
[ 113.958350][ T3282] pgalloc_tag_sub.part.66+0x154/0x164
[ 113.959000][ T3282] pgalloc_tag_sub+0x14/0x1c
[ 113.959539][ T3282] free_unref_page+0xf4/0x4b8
[ 113.960096][ T3282] __folio_put+0xd4/0x120
[ 113.960614][ T3282] folio_put+0x24/0x50
[ 113.961103][ T3282] unpoison_memory+0x4f0/0x5b0
[ 113.961678][ T3282] hwpoison_unpoison+0x30/0x48 [hwpoison_inject]
[ 113.962436][ T3282] simple_attr_write_xsigned.isra.34+0xec/0x1cc
[ 113.963183][ T3282] simple_attr_write+0x38/0x48
[ 113.963750][ T3282] debugfs_attr_write+0x54/0x80
[ 113.964330][ T3282] full_proxy_write+0x68/0x98
[ 113.964880][ T3282] vfs_write+0xdc/0x4d0
[ 113.965372][ T3282] ksys_write+0x78/0x100
[ 113.965875][ T3282] __arm64_sys_write+0x24/0x30
[ 113.966440][ T3282] invoke_syscall+0x7c/0x104
[ 113.966984][ T3282] el0_svc_common.constprop.1+0x88/0x104
[ 113.967652][ T3282] do_el0_svc+0x2c/0x38
[ 113.968893][ T3282] el0_svc+0x3c/0x1b8
[ 113.969379][ T3282] el0t_64_sync_handler+0x98/0xbc
[ 113.969980][ T3282] el0t_64_sync+0x19c/0x1a0
[ 113.970511][ T3282] ---[ end trace 0000000000000000 ]---
To fix this, clear the page tag reference after the page got isolated
and accounted for.
Link: https://lkml.kernel.org/r/20240825163649.33294-1-hao.ge@linux.dev
Fixes:
|
||
Suren Baghdasaryan
|
a8fc28dad6 |
alloc_tag: introduce clear_page_tag_ref() helper function
In several cases we are freeing pages which were not allocated using
common page allocators. For such cases, in order to keep allocation
accounting correct, we should clear the page tag to indicate that the page
being freed is expected to not have a valid allocation tag. Introduce
clear_page_tag_ref() helper function to be used for this.
Link: https://lkml.kernel.org/r/20240813150758.855881-1-surenb@google.com
Fixes:
|
||
Kirill A. Shutemov
|
807174a93d |
mm: fix endless reclaim on machines with unaccepted memory
Unaccepted memory is considered unusable free memory, which is not counted
as free on the zone watermark check. This causes get_page_from_freelist()
to accept more memory to hit the high watermark, but it creates problems
in the reclaim path.
The reclaim path encounters a failed zone watermark check and attempts to
reclaim memory. This is usually successful, but if there is little or no
reclaimable memory, it can result in endless reclaim with little to no
progress. This can occur early in the boot process, just after start of
the init process when the only reclaimable memory is the page cache of the
init executable and its libraries.
Make unaccepted memory free from watermark check point of view. This way
unaccepted memory will never be the trigger of memory reclaim. Accept
more memory in the get_page_from_freelist() if needed.
Link: https://lkml.kernel.org/r/20240809114854.3745464-2-kirill.shutemov@linux.intel.com
Fixes:
|
||
Pasha Tatashin
|
9d85731110 |
mm: don't account memmap per-node
Fix invalid access to pgdat during hot-remove operation:
ndctl users reported a GPF when trying to destroy a namespace:
$ ndctl destroy-namespace all -r all -f
Segmentation fault
dmesg:
Oops: general protection fault, probably for
non-canonical address 0xdffffc0000005650: 0000 [#1] PREEMPT SMP KASAN
PTI
KASAN: probably user-memory-access in range
[0x000000000002b280-0x000000000002b287]
CPU: 26 UID: 0 PID: 1868 Comm: ndctl Not tainted 6.11.0-rc1 #1
Hardware name: Dell Inc. PowerEdge R640/08HT8T, BIOS
2.20.1 09/13/2023
RIP: 0010:mod_node_page_state+0x2a/0x110
cxl-test users report a GPF when trying to unload the test module:
$ modrpobe -r cxl-test
dmesg
BUG: unable to handle page fault for address: 0000000000004200
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 UID: 0 PID: 1076 Comm: modprobe Tainted: G O N 6.11.0-rc1 #197
Tainted: [O]=OOT_MODULE, [N]=TEST
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/15
RIP: 0010:mod_node_page_state+0x6/0x90
Currently, when memory is hot-plugged or hot-removed the accounting is
done based on the assumption that memmap is allocated from the same node
as the hot-plugged/hot-removed memory, which is not always the case.
In addition, there are challenges with keeping the node id of the memory
that is being remove to the time when memmap accounting is actually
performed: since this is done after remove_pfn_range_from_zone(), and
also after remove_memory_block_devices(). Meaning that we cannot use
pgdat nor walking though memblocks to get the nid.
Given all of that, account the memmap overhead system wide instead.
For this we are going to be using global atomic counters, but given that
memmap size is rarely modified, and normally is only modified either
during early boot when there is only one CPU, or under a hotplug global
mutex lock, therefore there is no need for per-cpu optimizations.
Also, while we are here rename nr_memmap to nr_memmap_pages, and
nr_memmap_boot to nr_memmap_boot_pages to be self explanatory that the
units are in page count.
[pasha.tatashin@soleen.com: address a few nits from David Hildenbrand]
Link: https://lkml.kernel.org/r/20240809191020.1142142-4-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20240809191020.1142142-4-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20240808213437.682006-4-pasha.tatashin@soleen.com
Fixes:
|
||
Qais Yousef
|
ae04f69de0 |
sched/rt: Rename realtime_{prio, task}() to rt_or_dl_{prio, task}()
Some find the name realtime overloaded. Use rt_or_dl() as an alternative, hopefully better, name. Suggested-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Qais Yousef <qyousef@layalina.io> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240610192018.1567075-4-qyousef@layalina.io |
||
|
Qais Yousef
|
130fd056dd |
sched/rt: Clean up usage of rt_task()
rt_task() checks if a task has RT priority. But depends on your dictionary, this could mean it belongs to RT class, or is a 'realtime' task, which includes RT and DL classes. Since this has caused some confusion already on discussion [1], it seemed a clean up is due. I define the usage of rt_task() to be tasks that belong to RT class. Make sure that it returns true only for RT class and audit the users and replace the ones required the old behavior with the new realtime_task() which returns true for RT and DL classes. Introduce similar realtime_prio() to create similar distinction to rt_prio() and update the users that required the old behavior to use the new function. Move MAX_DL_PRIO to prio.h so it can be used in the new definitions. Document the functions to make it more obvious what is the difference between them. PI-boosted tasks is a factor that must be taken into account when choosing which function to use. Rename task_is_realtime() to realtime_task_policy() as the old name is confusing against the new realtime_task(). No functional changes were intended. [1] https://lore.kernel.org/lkml/20240506100509.GL40213@noisy.programming.kicks-ass.net/ Signed-off-by: Qais Yousef <qyousef@layalina.io> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Phil Auld <pauld@redhat.com> Reviewed-by: "Steven Rostedt (Google)" <rostedt@goodmis.org> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://lore.kernel.org/r/20240610192018.1567075-2-qyousef@layalina.io |
||
Li Zhijian
|
66eca1021a |
mm/page_alloc: fix pcp->count race between drain_pages_zone() vs __rmqueue_pcplist()
It's expected that no page should be left in pcp_list after calling
zone_pcp_disable() in offline_pages(). Previously, it's observed that
offline_pages() gets stuck [1] due to some pages remaining in pcp_list.
Cause:
There is a race condition between drain_pages_zone() and __rmqueue_pcplist()
involving the pcp->count variable. See below scenario:
CPU0 CPU1
---------------- ---------------
spin_lock(&pcp->lock);
__rmqueue_pcplist() {
zone_pcp_disable() {
/* list is empty */
if (list_empty(list)) {
/* add pages to pcp_list */
alloced = rmqueue_bulk()
mutex_lock(&pcp_batch_high_lock)
...
__drain_all_pages() {
drain_pages_zone() {
/* read pcp->count, it's 0 here */
count = READ_ONCE(pcp->count)
/* 0 means nothing to drain */
/* update pcp->count */
pcp->count += alloced << order;
...
...
spin_unlock(&pcp->lock);
In this case, after calling zone_pcp_disable() though, there are still some
pages in pcp_list. And these pages in pcp_list are neither movable nor
isolated, offline_pages() gets stuck as a result.
Solution:
Expand the scope of the pcp->lock to also protect pcp->count in
drain_pages_zone(), to ensure no pages are left in the pcp list after
zone_pcp_disable()
[1] https://lore.kernel.org/linux-mm/6a07125f-e720-404c-b2f9-e55f3f166e85@fujitsu.com/
Link: https://lkml.kernel.org/r/20240723064428.1179519-1-lizhijian@fujitsu.com
Fixes:
|
||
|
Suren Baghdasaryan
|
b3bebe4430 |
alloc_tag: outline and export free_reserved_page()
Outline and export free_reserved_page() because modules use it and it in
turn uses page_ext_{get|put} which should not be exported. The same
result could be obtained by outlining {get|put}_page_tag_ref() but that
would have higher performance impact as these functions are used in more
performance critical paths.
Link: https://lkml.kernel.org/r/20240717212844.2749975-1-surenb@google.com
Fixes:
|
||
Joel Granados
|
78eb4ea25c |
sysctl: treewide: constify the ctl_table argument of proc_handlers
const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.
This patch has been generated by the following coccinelle script:
```
virtual patch
@r1@
identifier ctl, write, buffer, lenp, ppos;
identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
@@
int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int write, void *buffer, size_t *lenp, loff_t *ppos);
@r2@
identifier func, ctl, write, buffer, lenp, ppos;
@@
int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int write, void *buffer, size_t *lenp, loff_t *ppos)
{ ... }
@r3@
identifier func;
@@
int func(
- struct ctl_table *
+ const struct ctl_table *
,int , void *, size_t *, loff_t *);
@r4@
identifier func, ctl;
@@
int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int , void *, size_t *, loff_t *);
@r5@
identifier func, write, buffer, lenp, ppos;
@@
int func(
- struct ctl_table *
+ const struct ctl_table *
,int write, void *buffer, size_t *lenp, loff_t *ppos);
```
* Code formatting was adjusted in xfs_sysctl.c to comply with code
conventions. The xfs_stats_clear_proc_handler,
xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
adjusted.
* The ctl_table argument in proc_watchdog_common was const qualified.
This is called from a proc_handler itself and is calling back into
another proc_handler, making it necessary to change it as part of the
proc_handler migration.
Co-developed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Co-developed-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
||
Vlastimil Babka
|
53dabce265 |
mm, page_alloc: put should_fail_alloc_page() back behing CONFIG_FAIL_PAGE_ALLOC
This mostly reverts commit
|
||
Wei Yang
|
f6953e22af |
mm/page_alloc: put __free_pages_core() in __meminit section
__free_pages_core() is only used in bootmem init and hot-add memory init path. Let's put it in __meminit section. Link: https://lkml.kernel.org/r/20240706061615.30322-1-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
|
Wei Yang
|
689d92cc81 |
mm/page_alloc: remove prefetchw() on freeing page to buddy system
The prefetchw() is introduced from an ancient patch[1].
The change log says:
The basic idea is to free higher order pages instead of going
through every single one. Also, some unnecessary atomic operations
are done away with and replaced with non-atomic equivalents, and
prefetching is done where it helps the most. For a more in-depth
discusion of this patch, please see the linux-ia64 archives (topic
is "free bootmem feedback patch").
So there are several changes improve the bootmem freeing, in which the
most basic idea is freeing higher order pages. And as Matthew says,
"Itanium CPUs of this era had no prefetchers."
I did 10 round bootup tests before and after this change, the data doesn't
prove prefetchw() help speeding up bootmem freeing. The sum of the 10
round bootmem freeing time after prefetchw() removal even 5.2% faster than
before.
[1]: https://lore.kernel.org/linux-ia64/40F46962.4090604@sgi.com/
Link: https://lkml.kernel.org/r/20240702020931.7061-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
||
Kefeng Wang
|
593a10dabe |
mm: refactor folio_undo_large_rmappable()
Folios of order <= 1 are not in deferred list, the check of order is added
into folio_undo_large_rmappable() from commit
|
||
|
Wei Yang
|
08af2c12e3 |
mm/page_alloc: reword the comment of buddy_merge_likely()
For page with order O, we are checking its order (O + 1)'s buddy. If it is free, we would like to put it to the tail and expect it would be merged to a page with order (O + 2). Reword the comment to reflect it. Link: https://lkml.kernel.org/r/20240619010612.20740-4-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
|
Wei Yang
|
b719efa22d |
mm/page_alloc: fix a typo in comment about GFP flag
The GFP flags used to choose the zonelist is __GFP_THISNODE. Let's change it to what exactly it should be. Link: https://lkml.kernel.org/r/20240619010612.20740-3-richard.weiyang@gmail.com Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
David Hildenbrand
|
5062574422 |
mm/memory_hotplug: skip adjust_managed_page_count() for PageOffline() pages when offlining
We currently have a hack for virtio-mem in place to handle memory offlining with PageOffline pages for which we already adjusted the managed page count. Let's enlighten memory offlining code so we can get rid of that hack, and document the situation. Link: https://lkml.kernel.org/r/20240607090939.89524-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Oscar Salvador <osalvador@suse.de> Cc: Alexander Potapenko <glider@google.com> Cc: Dexuan Cui <decui@microsoft.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eugenio Pérez <eperezma@redhat.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Marco Elver <elver@google.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Wei Liu <wei.liu@kernel.org> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
|
David Hildenbrand
|
503b158fc3 |
mm/memory_hotplug: initialize memmap of !ZONE_DEVICE with PageOffline() instead of PageReserved()
We currently initialize the memmap such that PG_reserved is set and the refcount of the page is 1. In virtio-mem code, we have to manually clear that PG_reserved flag to make memory offlining with partially hotplugged memory blocks possible: has_unmovable_pages() would otherwise bail out on such pages. We want to avoid PG_reserved where possible and move to typed pages instead. Further, we want to further enlighten memory offlining code about PG_offline: offline pages in an online memory section. One example is handling managed page count adjustments in a cleaner way during memory offlining. So let's initialize the pages with PG_offline instead of PG_reserved. generic_online_page()->__free_pages_core() will now clear that flag before handing that memory to the buddy. Note that the page refcount is still 1 and would forbid offlining of such memory except when special care is take during GOING_OFFLINE as currently only implemented by virtio-mem. With this change, we can now get non-PageReserved() pages in the XEN balloon list. From what I can tell, that can already happen via decrease_reservation(), so that should be fine. HV-balloon should not really observe a change: partial online memory blocks still cannot get surprise-offlined, because the refcount of these PageOffline() pages is 1. Update virtio-mem, HV-balloon and XEN-balloon code to be aware that hotplugged pages are now PageOffline() instead of PageReserved() before they are handed over to the buddy. We'll leave the ZONE_DEVICE case alone for now. Note that self-hosted vmemmap pages will no longer be marked as reserved. This matches ordinary vmemmap pages allocated from the buddy during memory hotplug. Now, really only vmemmap pages allocated from memblock during early boot will be marked reserved. Existing PageReserved() checks seem to be handling all relevant cases correctly even after this change. Link: https://lkml.kernel.org/r/20240607090939.89524-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Oscar Salvador <osalvador@suse.de> [generic memory-hotplug bits] Cc: Alexander Potapenko <glider@google.com> Cc: Dexuan Cui <decui@microsoft.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eugenio Pérez <eperezma@redhat.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Marco Elver <elver@google.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Wei Liu <wei.liu@kernel.org> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
|
David Hildenbrand
|
13c526540b |
mm: pass meminit_context to __free_pages_core()
Patch series "mm/memory_hotplug: use PageOffline() instead of PageReserved() for !ZONE_DEVICE". This can be a considered a long-overdue follow-up to some parts of [1]. The patches are based on [2], but they are not strictly required -- just makes it clearer why we can use adjust_managed_page_count() for memory hotplug without going into details about highmem. We stop initializing pages with PageReserved() in memory hotplug code -- except when dealing with ZONE_DEVICE for now. Instead, we use PageOffline(): all pages are initialized to PageOffline() when onlining a memory section, and only the ones actually getting exposed to the system/page allocator will get PageOffline cleared. This way, we enlighten memory hotplug more about PageOffline() pages and can cleanup some hacks we have in virtio-mem code. What about ZONE_DEVICE? PageOffline() is wrong, but we might just stop using PageReserved() for them later by simply checking for is_zone_device_page() at suitable places. That will be a separate patch set / proposal. This primarily affects virtio-mem, HV-balloon and XEN balloon. I only briefly tested with virtio-mem, which benefits most from these cleanups. [1] https://lore.kernel.org/all/20191024120938.11237-1-david@redhat.com/ [2] https://lkml.kernel.org/r/20240607083711.62833-1-david@redhat.com This patch (of 3): In preparation for further changes, let's teach __free_pages_core() about the differences of memory hotplug handling. Move the memory hotplug specific handling from generic_online_page() to __free_pages_core(), use adjust_managed_page_count() on the memory hotplug path, and spell out why memory freed via memblock cannot currently use adjust_managed_page_count(). [david@redhat.com: add missed CONFIG_DEFERRED_STRUCT_PAGE_INIT] Link: https://lkml.kernel.org/r/b72e6efd-fb0a-459c-b1a0-88a98e5b19e2@redhat.com [david@redhat.com: fix up the memblock comment, per Oscar] Link: https://lkml.kernel.org/r/2ed64218-7f3b-4302-a5dc-27f060654fe2@redhat.com [david@redhat.com: add the parameter name also in the declaration] Link: https://lkml.kernel.org/r/ca575956-f0dd-4fb9-a307-6b7621681ed9@redhat.com Link: https://lkml.kernel.org/r/20240607090939.89524-1-david@redhat.com Link: https://lkml.kernel.org/r/20240607090939.89524-2-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dexuan Cui <decui@microsoft.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eugenio Pérez <eperezma@redhat.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Marco Elver <elver@google.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Wei Liu <wei.liu@kernel.org> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
|
David Hildenbrand
|
e4d970acfb |
mm/page_alloc: clear PageBuddy using __ClearPageBuddy() for bad pages
Let's stop using page_mapcount_reset() and clear PageBuddy using __ClearPageBuddy() instead. Link: https://lkml.kernel.org/r/20240529111904.2069608-5-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org> [zram/zsmalloc workloads] Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
Sourav Panda
|
15995a3524 |
mm: report per-page metadata information
Today, we do not have any observability of per-page metadata and how much it takes away from the machine capacity. Thus, we want to describe the amount of memory that is going towards per-page metadata, which can vary depending on build configuration, machine architecture, and system use. This patch adds 2 fields to /proc/vmstat that can used as shown below: Accounting per-page metadata allocated by boot-allocator: /proc/vmstat:nr_memmap_boot * PAGE_SIZE Accounting per-page metadata allocated by buddy-allocator: /proc/vmstat:nr_memmap * PAGE_SIZE Accounting total Perpage metadata allocated on the machine: (/proc/vmstat:nr_memmap_boot + /proc/vmstat:nr_memmap) * PAGE_SIZE Utility for userspace: Observability: Describe the amount of memory overhead that is going to per-page metadata on the system at any given time since this overhead is not currently observable. Debugging: Tracking the changes or absolute value in struct pages can help detect anomalies as they can be correlated with other metrics in the machine (e.g., memtotal, number of huge pages, etc). page_ext overheads: Some kernel features such as page_owner page_table_check that use page_ext can be optionally enabled via kernel parameters. Having the total per-page metadata information helps users precisely measure impact. Furthermore, page-metadata metrics will reflect the amount of struct pages reliquished (or overhead reduced) when hugetlbfs pages are reserved which will vary depending on whether hugetlb vmemmap optimization is enabled or not. For background and results see: lore.kernel.org/all/20240220214558.3377482-1-souravpanda@google.com Link: https://lkml.kernel.org/r/20240605222751.1406125-1-souravpanda@google.com Signed-off-by: Sourav Panda <souravpanda@google.com> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Chen Linxuan <chenlinxuan@uniontech.com> Cc: David Hildenbrand <david@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ivan Babrou <ivan@cloudflare.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tomas Mudrunka <tomas.mudrunka@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Xu <weixugc@google.com> Cc: Yang Yang <yang.yang29@zte.com.cn> Cc: Yosry Ahmed <yosryahmed@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
|
David Hildenbrand
|
7a581204b1 |
mm/highmem: reimplement totalhigh_pages() by walking zones
Patch series "mm/highmem: don't track highmem pages manually". Let's remove highmem special-casing from adjust_managed_page_count(), to result in less confusion why memblock manually adjusts totalram_pages, and __free_pages_core() only adjusts the zone's managed pages -- what about the highmem pages that adjust_managed_page_count() updates? Now, we only maintain totalram_pages and a zone's managed pages independent of highmem support. We can derive the number of highmem pages simply by looking at the relevant zone's managed pages. I don't think there is any particular fast path that needs a maximum-efficient totalhigh_pages() implementation. Note that highmem memory is currently initialized using free_highmem_page()->free_reserved_page(), not __free_pages_core(). In the future we might want to also use __free_pages_core() to initialize highmem memory, to make that less special, and consider moving totalram_pages updates into __free_pages_core() [1], so we can just use adjust_managed_page_count() in there as well. Booting a simple kernel in QEMU reveals no highmem accounting change: Before: Memory: 3095448K/3145208K available (14802K kernel code, 2073K rwdata, 5000K rodata, 740K init, 556K bss, 49760K reserved, 0K cma-reserved, 2244488K highmem) After: Memory: 3095276K/3145208K available (14802K kernel code, 2073K rwdata, 5000K rodata, 740K init, 556K bss, 49932K reserved, 0K cma-reserved, 2244488K highmem) [1] https://lkml.kernel.org/r/20240601133402.2675-1-richard.weiyang@gmail.com This patch (of 2): Can we get rid of the highmem ifdef in adjust_managed_page_count()? Likely yes: we don't have that many totalhigh_pages() users, and they all don't seem to be very performance critical. So let's implement totalhigh_pages() like nr_free_highpages(), collecting information from all zones. This is now similar to what we do in si_meminfo_node() to collect the per-node highmem page count. In the common case (single node, 3-4 zones), we really shouldn't care. We could optimize a bit further (only walk ZONE_HIGHMEM and ZONE_MOVABLE if required), but there doesn't seem a real need for that. [david@redhat.com: fix build bot complaint] Link: https://lkml.kernel.org/r/b57e5bc4-eb72-40e3-add4-57dfa6e03df6@redhat.com Link: https://lkml.kernel.org/r/20240607083711.62833-1-david@redhat.com Link: https://lkml.kernel.org/r/20240607083711.62833-2-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Wei Yang <richard.weiyang@gmail.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
||
yangge
|
bf14ed81f5 |
mm/page_alloc: Separate THP PCP into movable and non-movable categories
Since commit |
||
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David Hildenbrand
|
384a746bb5 |
Revert "mm: init_mlocked_on_free_v3"
There was insufficient review and no agreement that this is the right
approach.
There are serious flaws with the implementation that make processes using
mlock() not even work with simple fork() [1] and we get reliable crashes
when rebooting.
Further, simply because we might be unmapping a single PTE of a large
mlocked folio, we shouldn't zero out the whole folio.
... especially because the code can also *corrupt* urelated memory because
kernel_init_pages(page, folio_nr_pages(folio));
Could end up writing outside of the actual folio if we work with a tail
page.
Let's revert it. Once there is agreement that this is the right approach,
the issues were fixed and there was reasonable review and proper testing,
we can consider it again.
[1] https://lkml.kernel.org/r/4da9da2f-73e4-45fd-b62f-a8a513314057@redhat.com
Link: https://lkml.kernel.org/r/20240605091710.38961-1-david@redhat.com
Fixes:
|
||
Johannes Weiner
|
7cc5a5d650 |
mm: page_alloc: fix highatomic typing in multi-block buddies
Christoph reports a page allocator splat triggered by xfstests:
generic/176 214s ... [ 1204.507931] run fstests generic/176 at 2024-05-27 12:52:30
XFS (nvme0n1): Mounting V5 Filesystem cd936307-415f-48a3-b99d-a2d52ae1f273
XFS (nvme0n1): Ending clean mount
XFS (nvme1n1): Mounting V5 Filesystem ab3ee1a4-af62-4934-9a6a-6c2fde321850
XFS (nvme1n1): Ending clean mount
XFS (nvme1n1): Unmounting Filesystem ab3ee1a4-af62-4934-9a6a-6c2fde321850
XFS (nvme1n1): Mounting V5 Filesystem 7099b02d-9c58-4d1d-be1d-2cc472d12cd9
XFS (nvme1n1): Ending clean mount
------------[ cut here ]------------
page type is 3, passed migratetype is 1 (nr=512)
WARNING: CPU: 0 PID: 509870 at mm/page_alloc.c:645 expand+0x1c5/0x1f0
Modules linked in: i2c_i801 crc32_pclmul i2c_smbus [last unloaded: scsi_debug]
CPU: 0 PID: 509870 Comm: xfs_io Not tainted 6.10.0-rc1+ #2437
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:expand+0x1c5/0x1f0
Code: 05 16 70 bf 02 01 e8 ca fc ff ff 8b 54 24 34 44 89 e1 48 c7 c7 80 a2 28 83 48 89 c6 b8 01 00 3
RSP: 0018:ffffc90003b2b968 EFLAGS: 00010082
RAX: 0000000000000000 RBX: ffffffff83fa9480 RCX: 0000000000000000
RDX: 0000000000000005 RSI: 0000000000000027 RDI: 00000000ffffffff
RBP: 00000000001f2600 R08: 00000000fffeffff R09: 0000000000000001
R10: 0000000000000000 R11: ffffffff83676200 R12: 0000000000000009
R13: 0000000000000200 R14: 0000000000000001 R15: ffffea0007c98000
FS: 00007f72ca3d5780(0000) GS:ffff8881f9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f72ca1fff38 CR3: 00000001aa0c6002 CR4: 0000000000770ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<TASK>
? __warn+0x7b/0x120
? expand+0x1c5/0x1f0
? report_bug+0x191/0x1c0
? handle_bug+0x3c/0x80
? exc_invalid_op+0x17/0x70
? asm_exc_invalid_op+0x1a/0x20
? expand+0x1c5/0x1f0
? expand+0x1c5/0x1f0
__rmqueue_pcplist+0x3a9/0x730
get_page_from_freelist+0x7a0/0xf00
__alloc_pages_noprof+0x153/0x2e0
__folio_alloc_noprof+0x10/0xa0
__filemap_get_folio+0x16b/0x370
iomap_write_begin+0x496/0x680
While trying to service a movable allocation (page type 1), the page
allocator runs into a two-pageblock buddy on the movable freelist whose
second block is typed as highatomic (page type 3).
This inconsistency is caused by the highatomic reservation system
operating on single pageblocks, while MAX_ORDER can be bigger than that -
in this configuration, pageblock_order is 9 while MAX_PAGE_ORDER is 10.
The test case is observed to make several adjacent order-3 requests with
__GFP_DIRECT_RECLAIM cleared, which marks the surrounding block as
highatomic. Upon freeing, the blocks merge into an order-10 buddy. When
the highatomic pool is drained later on, this order-10 buddy gets moved
back to the movable list, but only the first pageblock is marked movable
again. A subsequent expand() of this buddy warns about the tail being of
a different type.
This is a long-standing bug that's surfaced by the recent block type
warnings added to the allocator. The consequences seem mostly benign, it
just results in odd behavior: the highatomic tail blocks are not properly
drained, instead they end up on the movable list first, then go back to
the highatomic list after an alloc-free cycle.
To fix this, make the highatomic reservation code aware that
allocations/buddies can be larger than a pageblock.
While it's an old quirk, the recently added type consistency warnings seem
to be the most prominent consequence of it. Set the Fixes: tag
accordingly to highlight this backporting dependency.
Link: https://lkml.kernel.org/r/20240530114203.GA1222079@cmpxchg.org
Fixes:
|
||
Baolin Wang
|
231f8c7127 |
mm: page_alloc: allowing mTHP compaction to capture the freed page directly
Currently, compaction_capture() does not allow lower-order allocations to
directly capture the movable free pages, even though lower-order
allocations might also be requesting movable pages, that can lead to more
compaction scanning. And, with the enablement of mTHP, such situations
will become more common.
Thus allowing lower-order (mTHP) allocations of movable page types
directly capture the movable free pages can avoid unnecessary compaction
scanning, meanwhile that won't pollute the movable pageblock. With
testing 1M mTHP compaction, it can be seen that compaction scanning is
significantly reduced.
mm-unstable patched
Ops Compaction pages isolated 116598741.00 120946702.00
Ops Compaction migrate scanned 1764870054.00 1488621550.00
Ops Compaction free scanned 7707879039.00 4986299318.00
Ops Compact scan efficiency 22.90 29.85
Ops Compaction cost 73797.69 72933.48
Link: https://lkml.kernel.org/r/8118a5d66a034736a48433beddaca60ed78577c4.1712892329.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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David Hildenbrand
|
7115936ac1 |
mm/page_alloc: use folio_mapped() in __alloc_contig_migrate_range()
We want to limit the use of page_mapcount() to the places where it is absolutely necessary. For tracing purposes, we use page_mapcount() in __alloc_contig_migrate_range(). Adding that mapcount to total_mapped sounds strange: total_migrated and total_reclaimed would count each page only once, not multiple times. But then, isolate_migratepages_range() adds each folio only once to the list. So for large folios, we would query the mapcount of the first page of the folio, which doesn't make too much sense for large folios. Let's simply use folio_mapped() * folio_nr_pages(), which makes more sense as nr_migratepages is also incremented by the number of pages in the folio in case of successful migration. Link: https://lkml.kernel.org/r/20240409192301.907377-11-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Chris Zankel <chris@zankel.net> Cc: Hugh Dickins <hughd@google.com> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Richard Chang <richardycc@google.com> Cc: Rich Felker <dalias@libc.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Yin Fengwei <fengwei.yin@intel.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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|
David Hildenbrand
|
05c5323b2a |
mm: track mapcount of large folios in single value
Let's track the mapcount of large folios in a single value. The mapcount of a large folio currently corresponds to the sum of the entire mapcount and all page mapcounts. This sum is what we actually want to know in folio_mapcount() and it is also sufficient for implementing folio_mapped(). With PTE-mapped THP becoming more important and more widely used, we want to avoid looping over all pages of a folio just to obtain the mapcount of large folios. The comment "In the common case, avoid the loop when no pages mapped by PTE" in folio_total_mapcount() does no longer hold for mTHP that are always mapped by PTE. Further, we are planning on using folio_mapcount() more frequently, and might even want to remove page mapcounts for large folios in some kernel configs. Therefore, allow for reading the mapcount of large folios efficiently and atomically without looping over any pages. Maintain the mapcount also for hugetlb pages for simplicity. Use the new mapcount to implement folio_mapcount() and folio_mapped(). Make page_mapped() simply call folio_mapped(). We can now get rid of folio_large_is_mapped(). _nr_pages_mapped is now only used in rmap code and for debugging purposes. Keep folio_nr_pages_mapped() around, but document that its use should be limited to rmap internals and debugging purposes. This change implies one additional atomic add/sub whenever mapping/unmapping (parts of) a large folio. As we now batch RMAP operations for PTE-mapped THP during fork(), during unmap/zap, and when PTE-remapping a PMD-mapped THP, and we adjust the large mapcount for a PTE batch only once, the added overhead in the common case is small. Only when unmapping individual pages of a large folio (e.g., during COW), the overhead might be bigger in comparison, but it's essentially one additional atomic operation. Note that before the new mapcount would overflow, already our refcount would overflow: each mapping requires a folio reference. Extend the focumentation of folio_mapcount(). Link: https://lkml.kernel.org/r/20240409192301.907377-5-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com> Cc: Chris Zankel <chris@zankel.net> Cc: Hugh Dickins <hughd@google.com> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Richard Chang <richardycc@google.com> Cc: Rich Felker <dalias@libc.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Matthew Wilcox (Oracle)
|
2542b1ac9a |
mm: inline destroy_large_folio() into __folio_put_large()
destroy_large_folio() has only one caller, move its contents there. Link: https://lkml.kernel.org/r/20240405153228.2563754-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Matthew Wilcox (Oracle)
|
5b8d75913a |
mm: combine free_the_page() and free_unref_page()
The pcp_allowed_order() check in free_the_page() was only being skipped by __folio_put_small() which is about to be rearranged. Link: https://lkml.kernel.org/r/20240405153228.2563754-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Baolin Wang
|
6303d1c553 |
mm: page_alloc: use the correct THP order for THP PCP
Commit |
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Joel Granados
|
7998df0b64 |
memory: remove the now superfluous sentinel element from ctl_table array
This commit comes at the tail end of a greater effort to remove the empty elements at the end of the ctl_table arrays (sentinels) which will reduce the overall build time size of the kernel and run time memory bloat by ~64 bytes per sentinel (further information Link : https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/) Remove sentinel from all files under mm/ that register a sysctl table. Link: https://lkml.kernel.org/r/20240328-jag-sysctl_remset_misc-v1-1-47c1463b3af2@samsung.com Signed-off-by: Joel Granados <j.granados@samsung.com> Reviewed-by: Muchun Song <muchun.song@linux.dev> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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York Jasper Niebuhr
|
ba42b524a0 |
mm: init_mlocked_on_free_v3
Implements the "init_mlocked_on_free" boot option. When this boot option
is enabled, any mlock'ed pages are zeroed on free. If
the pages are munlock'ed beforehand, no initialization takes place.
This boot option is meant to combat the performance hit of
"init_on_free" as reported in commit
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Baoquan He
|
0aac45663a |
mm/page_alloc.c: change the array-length to MIGRATE_PCPTYPES
Earlier, in commit
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Baoquan He
|
96a5c186ef |
mm/page_alloc.c: don't show protection in zone's ->lowmem_reserve[] for empty zone
On one node, for lower zone's ->lowmem_reserve[], it will show how much
memory is reserved in this lower zone to avoid excessive page allocation
from the relevant higher zone's fallback allocation.
However, currently lower zone's lowmem_reserve[] element will be filled
even though the relevant higher zone is empty. That doesnt' make sense
and can cause confusion.
E.g on node 0 of one system as below, it has zone
DMA/DMA32/NORMAL/MOVABLE/DEVICE, among them zone MOVABLE/DEVICE are the
highest and both are empty. In zone DMA/DMA32's protection array, we can
see that it has value for zone MOVABLE and DEVICE.
Node 0, zone DMA
......
pages free 2816
boost 0
min 7
low 10
high 13
spanned 4095
present 3998
managed 3840
cma 0
protection: (0, 1582, 23716, 23716, 23716)
......
Node 0, zone DMA32
pages free 403269
boost 0
min 753
low 1158
high 1563
spanned 1044480
present 487039
managed 405070
cma 0
protection: (0, 0, 22134, 22134, 22134)
......
Node 0, zone Normal
pages free 5423879
boost 0
min 10539
low 16205
high 21871
spanned 5767168
present 5767168
managed 5666438
cma 0
protection: (0, 0, 0, 0, 0)
......
Node 0, zone Movable
pages free 0
boost 0
min 32
low 32
high 32
spanned 0
present 0
managed 0
cma 0
protection: (0, 0, 0, 0, 0)
Node 0, zone Device
pages free 0
boost 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
cma 0
protection: (0, 0, 0, 0, 0)
Here, clear out the element value in lower zone's ->lowmem_reserve[] if the
relevant higher zone is empty.
And also replace space with tab in _deferred_grow_zone()
Link: https://lkml.kernel.org/r/20240326061134.1055295-7-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: "Mike Rapoport (IBM)" <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Baoquan He
|
bb8ea62daa |
mm/page_alloc.c: remove unneeded codes in !NUMA version of build_zonelists()
When CONFIG_NUMA=n, MAX_NUMNODES is always 1 because Kconfig item NODES_SHIFT depends on NUMA. So in !NUMA version of build_zonelists(), no need to bother with the two for loop because code execution won't enter them ever. Here, remove those unneeded codes in !NUMA version of build_zonelists(). [bhe@redhat.com: remove unused locals] Link: https://lkml.kernel.org/r/ZgQL1WOf9K88nLpQ@MiWiFi-R3L-srv Link: https://lkml.kernel.org/r/20240326061134.1055295-5-bhe@redhat.com Signed-off-by: Baoquan He <bhe@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: "Mike Rapoport (IBM)" <rppt@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Matthew Wilcox (Oracle)
|
2ace5a670e |
mm: make is_free_buddy_page() take a const argument
This function does not modify its argument; let the callers know that so they can make better optimisation decisions. Link: https://lkml.kernel.org/r/20240326171045.410737-6-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Baolin Wang
|
e42dfe4e0a |
mm: record the migration reason for struct migration_target_control
Patch series "make the hugetlb migration strategy consistent", v2. As discussed in previous thread [1], there is an inconsistency when handling hugetlb migration. When handling the migration of freed hugetlb, it prevents fallback to other NUMA nodes in alloc_and_dissolve_hugetlb_folio(). However, when dealing with in-use hugetlb, it allows fallback to other NUMA nodes in alloc_hugetlb_folio_nodemask(), which can break the per-node hugetlb pool and might result in unexpected failures when node bound workloads doesn't get what is asssumed available. This patchset tries to make the hugetlb migration strategy more clear and consistent. Please find details in each patch. [1] https://lore.kernel.org/all/6f26ce22d2fcd523418a085f2c588fe0776d46e7.1706794035.git.baolin.wang@linux.alibaba.com/ This patch (of 2): To support different hugetlb allocation strategies during hugetlb migration based on various migration reasons, record the migration reason in the migration_target_control structure as a preparation. Link: https://lkml.kernel.org/r/cover.1709719720.git.baolin.wang@linux.alibaba.com Link: https://lkml.kernel.org/r/7b95d4981e07211f57139fc5b1f7ce91b920cee4.1709719720.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
883dd161e9 |
mm: page_alloc: batch vmstat updates in expand()
expand() currently updates vmstat for every subpage. This is unnecessary, since they're all of the same zone and migratetype. Count added pages locally, then do a single vmstat update. Link: https://lkml.kernel.org/r/20240327190111.GC7597@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Vlastimil Babka
|
e1f42a577f |
mm: page_alloc: change move_freepages() to __move_freepages_block()
The function is now supposed to be called only on a single pageblock and checks start_pfn and end_pfn accordingly. Rename it to make this more obvious and drop the end_pfn parameter which can be determined trivially and none of the callers use it for anything else. Also make the (now internal) end_pfn exclusive, which is more common. Link: https://lkml.kernel.org/r/81b1d642-2ec0-49f5-89fc-19a3828419ff@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Zi Yan <ziy@nvidia.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
e0932b6c1f |
mm: page_alloc: consolidate free page accounting
Free page accounting currently happens a bit too high up the call stack, where it has to deal with guard pages, compaction capturing, block stealing and even page isolation. This is subtle and fragile, and makes it difficult to hack on the code. Now that type violations on the freelists have been fixed, push the accounting down to where pages enter and leave the freelist. [hannes@cmpxchg.org: undo unrelated drive-by line wrap] Link: https://lkml.kernel.org/r/20240327185736.GA7597@cmpxchg.org [hannes@cmpxchg.org: remove unused page parameter from account_freepages()] Link: https://lkml.kernel.org/r/20240327185831.GB7597@cmpxchg.org [baolin.wang@linux.alibaba.com: fix free page accounting] Link: https://lkml.kernel.org/r/a2a48baca69f103aa431fd201f8a06e3b95e203d.1712648441.git.baolin.wang@linux.alibaba.com [andriy.shevchenko@linux.intel.com: avoid defining unused function] Link: https://lkml.kernel.org/r/20240423161506.2637177-1-andriy.shevchenko@linux.intel.com Link: https://lkml.kernel.org/r/20240320180429.678181-11-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
fd919a85cd |
mm: page_isolation: prepare for hygienic freelists
Page isolation currently sets MIGRATE_ISOLATE on a block, then drops
zone->lock and scans the block for straddling buddies to split up.
Because this happens non-atomically wrt the page allocator, it's possible
for allocations to get a buddy whose first block is a regular pcp
migratetype but whose tail is isolated. This means that in certain cases
memory can still be allocated after isolation. It will also trigger the
freelist type hygiene warnings in subsequent patches.
start_isolate_page_range()
isolate_single_pageblock()
set_migratetype_isolate(tail)
lock zone->lock
move_freepages_block(tail) // nop
set_pageblock_migratetype(tail)
unlock zone->lock
__rmqueue_smallest()
del_page_from_freelist(head)
expand(head, head_mt)
WARN(head_mt != tail_mt)
start_pfn = ALIGN_DOWN(MAX_ORDER_NR_PAGES)
for (pfn = start_pfn, pfn < end_pfn)
if (PageBuddy())
split_free_page(head)
Introduce a variant of move_freepages_block() provided by the allocator
specifically for page isolation; it moves free pages, converts the block,
and handles the splitting of straddling buddies while holding zone->lock.
The allocator knows that pageblocks and buddies are always naturally
aligned, which means that buddies can only straddle blocks if they're
actually >pageblock_order. This means the search-and-split part can be
simplified compared to what page isolation used to do.
Also tighten up the page isolation code around the expectations of which
pages can be large, and how they are freed.
Based on extensive discussions with and invaluable input from Zi Yan.
[hannes@cmpxchg.org: work around older gcc warning]
Link: https://lkml.kernel.org/r/20240321142426.GB777580@cmpxchg.org
Link: https://lkml.kernel.org/r/20240320180429.678181-10-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Zi Yan
|
f37c0f6876 |
mm: page_alloc: set migratetype inside move_freepages()
This avoids changing migratetype after move_freepages() or move_freepages_block(), which is error prone. It also prepares for upcoming changes to fix move_freepages() not moving free pages partially in the range. Link: https://lkml.kernel.org/r/20240320180429.678181-9-hannes@cmpxchg.org Signed-off-by: Zi Yan <ziy@nvidia.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
55612e80e7 |
mm: page_alloc: close migratetype race between freeing and stealing
There are three freeing paths that read the page's migratetype optimistically before grabbing the zone lock. When this races with block stealing, those pages go on the wrong freelist. The paths in question are: - when freeing >costly orders that aren't THP - when freeing pages to the buddy upon pcp lock contention - when freeing pages that are isolated - when freeing pages initially during boot - when freeing the remainder in alloc_pages_exact() - when "accepting" unaccepted VM host memory before first use - when freeing pages during unpoisoning None of these are so hot that they would need this optimization at the cost of hampering defrag efforts. Especially when contrasted with the fact that the most common buddy freeing path - free_pcppages_bulk - is checking the migratetype under the zone->lock just fine. In addition, isolated pages need to look up the migratetype under the lock anyway, which adds branches to the locked section, and results in a double lookup when the pages are in fact isolated. Move the lookups into the lock. Link: https://lkml.kernel.org/r/20240320180429.678181-8-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
c0cd6f557b |
mm: page_alloc: fix freelist movement during block conversion
Currently, page block type conversion during fallbacks, atomic reservations and isolation can strand various amounts of free pages on incorrect freelists. For example, fallback stealing moves free pages in the block to the new type's freelists, but then may not actually claim the block for that type if there aren't enough compatible pages already allocated. In all cases, free page moving might fail if the block straddles more than one zone, in which case no free pages are moved at all, but the block type is changed anyway. This is detrimental to type hygiene on the freelists. It encourages incompatible page mixing down the line (ask for one type, get another) and thus contributes to long-term fragmentation. Split the process into a proper transaction: check first if conversion will happen, then try to move the free pages, and only if that was successful convert the block to the new type. [baolin.wang@linux.alibaba.com: fix allocation failures with CONFIG_CMA] Link: https://lkml.kernel.org/r/a97697e0-45b0-4f71-b087-fdc7a1d43c0e@linux.alibaba.com Link: https://lkml.kernel.org/r/20240320180429.678181-7-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Tested-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
2dd482ba62 |
mm: page_alloc: fix move_freepages_block() range error
When a block is partially outside the zone of the cursor page, the function cuts the range to the pivot page instead of the zone start. This can leave large parts of the block behind, which encourages incompatible page mixing down the line (ask for one type, get another), and thus long-term fragmentation. This triggers reliably on the first block in the DMA zone, whose start_pfn is 1. The block is stolen, but everything before the pivot page (which was often hundreds of pages) is left on the old list. Link: https://lkml.kernel.org/r/20240320180429.678181-6-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
b54ccd3c6b |
mm: page_alloc: move free pages when converting block during isolation
When claiming a block during compaction isolation, move any remaining free pages to the correct freelists as well, instead of stranding them on the wrong list. Otherwise, this encourages incompatible page mixing down the line, and thus long-term fragmentation. Link: https://lkml.kernel.org/r/20240320180429.678181-5-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Tested-by: "Huang, Ying" <ying.huang@intel.com> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
e6cf9e1c4c |
mm: page_alloc: fix up block types when merging compatible blocks
The buddy allocator coalesces compatible blocks during freeing, but it doesn't update the types of the subblocks to match. When an allocation later breaks the chunk down again, its pieces will be put on freelists of the wrong type. This encourages incompatible page mixing (ask for one type, get another), and thus long-term fragmentation. Update the subblocks when merging a larger chunk, such that a later expand() will maintain freelist type hygiene. Link: https://lkml.kernel.org/r/20240320180429.678181-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Tested-by: "Huang, Ying" <ying.huang@intel.com> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
9cbe97bad5 |
mm: page_alloc: optimize free_unref_folios()
Move direct freeing of isolated pages to the lock-breaking block in the second loop. This saves an unnecessary migratetype reassessment. Minor comment and local variable scoping cleanups. Link: https://lkml.kernel.org/r/20240320180429.678181-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: David Hildenbrand <david@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Johannes Weiner
|
17edeb5d3f |
mm: page_alloc: remove pcppage migratetype caching
Patch series "mm: page_alloc: freelist migratetype hygiene", v4.
The page allocator's mobility grouping is intended to keep unmovable pages
separate from reclaimable/compactable ones to allow on-demand
defragmentation for higher-order allocations and huge pages.
Currently, there are several places where accidental type mixing occurs:
an allocation asks for a page of a certain migratetype and receives
another. This ruins pageblocks for compaction, which in turn makes
allocating huge pages more expensive and less reliable.
The series addresses those causes. The last patch adds type checks on all
freelist movements to prevent new violations being introduced.
The benefits can be seen in a mixed workload that stresses the machine
with a memcache-type workload and a kernel build job while periodically
attempting to allocate batches of THP. The following data is aggregated
over 50 consecutive defconfig builds:
VANILLA PATCHED
Hugealloc Time mean 165843.93 ( +0.00%) 113025.88 ( -31.85%)
Hugealloc Time stddev 158957.35 ( +0.00%) 114716.07 ( -27.83%)
Kbuild Real time 310.24 ( +0.00%) 300.73 ( -3.06%)
Kbuild User time 1271.13 ( +0.00%) 1259.42 ( -0.92%)
Kbuild System time 582.02 ( +0.00%) 559.79 ( -3.81%)
THP fault alloc 30585.14 ( +0.00%) 40853.62 ( +33.57%)
THP fault fallback 36626.46 ( +0.00%) 26357.62 ( -28.04%)
THP fault fail rate % 54.49 ( +0.00%) 39.22 ( -27.53%)
Pagealloc fallback 1328.00 ( +0.00%) 1.00 ( -99.85%)
Pagealloc type mismatch 181009.50 ( +0.00%) 0.00 ( -100.00%)
Direct compact stall 434.56 ( +0.00%) 257.66 ( -40.61%)
Direct compact fail 421.70 ( +0.00%) 249.94 ( -40.63%)
Direct compact success 12.86 ( +0.00%) 7.72 ( -37.09%)
Direct compact success rate % 2.86 ( +0.00%) 2.82 ( -0.96%)
Compact daemon scanned migrate 3370059.62 ( +0.00%) 3612054.76 ( +7.18%)
Compact daemon scanned free 7718439.20 ( +0.00%) 5386385.02 ( -30.21%)
Compact direct scanned migrate 309248.62 ( +0.00%) 176721.04 ( -42.85%)
Compact direct scanned free 433582.84 ( +0.00%) 315727.66 ( -27.18%)
Compact migrate scanned daemon % 91.20 ( +0.00%) 94.48 ( +3.56%)
Compact free scanned daemon % 94.58 ( +0.00%) 94.42 ( -0.16%)
Compact total migrate scanned 3679308.24 ( +0.00%) 3788775.80 ( +2.98%)
Compact total free scanned 8152022.04 ( +0.00%) 5702112.68 ( -30.05%)
Alloc stall 872.04 ( +0.00%) 5156.12 ( +490.71%)
Pages kswapd scanned 510645.86 ( +0.00%) 3394.94 ( -99.33%)
Pages kswapd reclaimed 134811.62 ( +0.00%) 2701.26 ( -98.00%)
Pages direct scanned 99546.06 ( +0.00%) 376407.52 ( +278.12%)
Pages direct reclaimed 62123.40 ( +0.00%) 289535.70 ( +366.06%)
Pages total scanned 610191.92 ( +0.00%) 379802.46 ( -37.76%)
Pages scanned kswapd % 76.36 ( +0.00%) 0.10 ( -98.58%)
Swap out 12057.54 ( +0.00%) 15022.98 ( +24.59%)
Swap in 209.16 ( +0.00%) 256.48 ( +22.52%)
File refaults 17701.64 ( +0.00%) 11765.40 ( -33.53%)
Huge page success rate is higher, allocation latencies are shorter and
more predictable.
Stealing (fallback) rate is drastically reduced. Notably, while the
vanilla kernel keeps doing fallbacks on an ongoing basis, the patched
kernel enters a steady state once the distribution of block types is
adequate for the workload. Steals over 50 runs:
VANILLA PATCHED
1504.0 227.0
1557.0 6.0
1391.0 13.0
1080.0 26.0
1057.0 40.0
1156.0 6.0
805.0 46.0
736.0 20.0
1747.0 2.0
1699.0 34.0
1269.0 13.0
1858.0 12.0
907.0 4.0
727.0 2.0
563.0 2.0
3094.0 2.0
10211.0 3.0
2621.0 1.0
5508.0 2.0
1060.0 2.0
538.0 3.0
5773.0 2.0
2199.0 0.0
3781.0 2.0
1387.0 1.0
4977.0 0.0
2865.0 1.0
1814.0 1.0
3739.0 1.0
6857.0 0.0
382.0 0.0
407.0 1.0
3784.0 0.0
297.0 0.0
298.0 0.0
6636.0 0.0
4188.0 0.0
242.0 0.0
9960.0 0.0
5816.0 0.0
354.0 0.0
287.0 0.0
261.0 0.0
140.0 1.0
2065.0 0.0
312.0 0.0
331.0 0.0
164.0 0.0
465.0 1.0
219.0 0.0
Type mismatches are down too. Those count every time an allocation
request asks for one migratetype and gets another. This can still occur
minimally in the patched kernel due to non-stealing fallbacks, but it's
quite rare and follows the pattern of overall fallbacks - once the block
type distribution settles, mismatches cease as well:
VANILLA: PATCHED:
182602.0 268.0
135794.0 20.0
88619.0 19.0
95973.0 0.0
129590.0 0.0
129298.0 0.0
147134.0 0.0
230854.0 0.0
239709.0 0.0
137670.0 0.0
132430.0 0.0
65712.0 0.0
57901.0 0.0
67506.0 0.0
63565.0 4.0
34806.0 0.0
42962.0 0.0
32406.0 0.0
38668.0 0.0
61356.0 0.0
57800.0 0.0
41435.0 0.0
83456.0 0.0
65048.0 0.0
28955.0 0.0
47597.0 0.0
75117.0 0.0
55564.0 0.0
38280.0 0.0
52404.0 0.0
26264.0 0.0
37538.0 0.0
19671.0 0.0
30936.0 0.0
26933.0 0.0
16962.0 0.0
44554.0 0.0
46352.0 0.0
24995.0 0.0
35152.0 0.0
12823.0 0.0
21583.0 0.0
18129.0 0.0
31693.0 0.0
28745.0 0.0
33308.0 0.0
31114.0 0.0
35034.0 0.0
12111.0 0.0
24885.0 0.0
Compaction work is markedly reduced despite much better THP rates.
In the vanilla kernel, reclaim seems to have been driven primarily by
watermark boosting that happens as a result of fallbacks. With those all
but eliminated, watermarks average lower and kswapd does less work. The
uptick in direct reclaim is because THP requests have to fend for
themselves more often - which is intended policy right now. Aggregate
reclaim activity is lowered significantly, though.
This patch (of 10):
The idea behind the cache is to save get_pageblock_migratetype() lookups
during bulk freeing. A microbenchmark suggests this isn't helping,
though. The pcp migratetype can get stale, which means that bulk freeing
has an extra branch to check if the pageblock was isolated while on the
pcp.
While the variance overlaps, the cache write and the branch seem to make
this a net negative. The following test allocates and frees batches of
10,000 pages (~3x the pcp high marks to trigger flushing):
Before:
8,668.48 msec task-clock # 99.735 CPUs utilized ( +- 2.90% )
19 context-switches # 4.341 /sec ( +- 3.24% )
0 cpu-migrations # 0.000 /sec
17,440 page-faults # 3.984 K/sec ( +- 2.90% )
41,758,692,473 cycles # 9.541 GHz ( +- 2.90% )
126,201,294,231 instructions # 5.98 insn per cycle ( +- 2.90% )
25,348,098,335 branches # 5.791 G/sec ( +- 2.90% )
33,436,921 branch-misses # 0.26% of all branches ( +- 2.90% )
0.0869148 +- 0.0000302 seconds time elapsed ( +- 0.03% )
After:
8,444.81 msec task-clock # 99.726 CPUs utilized ( +- 2.90% )
22 context-switches # 5.160 /sec ( +- 3.23% )
0 cpu-migrations # 0.000 /sec
17,443 page-faults # 4.091 K/sec ( +- 2.90% )
40,616,738,355 cycles # 9.527 GHz ( +- 2.90% )
126,383,351,792 instructions # 6.16 insn per cycle ( +- 2.90% )
25,224,985,153 branches # 5.917 G/sec ( +- 2.90% )
32,236,793 branch-misses # 0.25% of all branches ( +- 2.90% )
0.0846799 +- 0.0000412 seconds time elapsed ( +- 0.05% )
A side effect is that this also ensures that pages whose pageblock gets
stolen while on the pcplist end up on the right freelist and we don't
perform potentially type-incompatible buddy merges (or skip merges when we
shouldn't), which is likely beneficial to long-term fragmentation
management, although the effects would be harder to measure. Settle for
simpler and faster code as justification here.
Link: https://lkml.kernel.org/r/20240320180429.678181-1-hannes@cmpxchg.org
Link: https://lkml.kernel.org/r/20240320180429.678181-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Tested-by: "Huang, Ying" <ying.huang@intel.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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