linux/mm
Gioh Kim 3643763834 mm/vmalloc.c: enhance vm_map_ram() comment
vm_map_ram() has a fragmentation problem when it cannot purge a
chunk(ie, 4M address space) if there is a pinning object in that
addresss space.  So it could consume all VMALLOC address space easily.

We can fix the fragmentation problem by using vmap instead of
vm_map_ram() but vmap() is known to be slow compared to vm_map_ram().
Minchan said vm_map_ram is 5 times faster than vmap in his tests.  So I
thought we should fix fragment problem of vm_map_ram because our
proprietary GPU driver has used it heavily.

On second thought, it's not an easy because we should reuse freed space
for solving the problem and it could make more IPI and bitmap operation
for searching hole.  It could mitigate API's goal which is very fast
mapping.  And even fragmentation problem wouldn't show in 64 bit
machine.

Another option is that the user should separate long-life and short-life
object and use vmap for long-life but vm_map_ram for short-life.  If we
inform the user about the characteristic of vm_map_ram the user can
choose one according to the page lifetime.

Let's add some notice messages to user.

[akpm@linux-foundation.org: tweak comment text]
Signed-off-by: Gioh Kim <gioh.kim@lge.com>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:35:55 -07:00
..
backing-dev.c bdi: avoid oops on device removal 2014-04-03 16:20:49 -07:00
balloon_compaction.c mm: print more details for bad_page() 2014-01-23 16:36:50 -08:00
bootmem.c mm/bootmem.c: remove unused local `map' 2013-11-13 12:09:09 +09:00
bounce.c block: Convert bio_for_each_segment() to bvec_iter 2013-11-23 22:33:49 -08:00
cleancache.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
compaction.c mm, compaction: determine isolation mode only once 2014-04-07 16:35:55 -07:00
debug-pagealloc.c
dmapool.c
fadvise.c teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long 2013-03-03 22:46:22 -05:00
failslab.c
filemap_xip.c seqcount: Add lockdep functionality to seqcount/seqlock structures 2013-11-06 12:40:26 +01:00
filemap.c mm: cleanup size checks in filemap_fault() and filemap_map_pages() 2014-04-07 16:35:53 -07:00
fremap.c mm: fix bad rss-counter if remap_file_pages raced migration 2014-03-19 16:21:49 -07:00
frontswap.c frontswap: fix incorrect zeroing and allocation size for frontswap_map 2013-06-12 16:29:46 -07:00
highmem.c
huge_memory.c mm: revert "thp: make MADV_HUGEPAGE check for mm->def_flags" 2014-04-07 16:35:51 -07:00
hugetlb_cgroup.c cgroup: drop const from @buffer of cftype->write_string() 2014-03-19 10:23:54 -04:00
hugetlb.c mm: fix 'ERROR: do not initialise globals to 0 or NULL' and coding style 2014-04-07 16:35:55 -07:00
hwpoison-inject.c mm/hwpoison: add '#' to hwpoison_inject 2014-01-21 16:19:48 -08:00
init-mm.c
internal.h mm/page-writeback.c: do not count anon pages as dirtyable memory 2014-01-29 16:22:39 -08:00
interval_tree.c
Kconfig mm: disable split page table lock for !MMU 2014-04-07 16:35:52 -07:00
Kconfig.debug
kmemcheck.c
kmemleak-test.c
kmemleak.c kmemleak: change some global variables to int 2014-04-03 16:20:50 -07:00
ksm.c mm: close PageTail race 2014-03-04 07:55:47 -08:00
list_lru.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
maccess.c
madvise.c mm/hwpoison: fix traversal of hugetlbfs pages to avoid printk flood 2013-09-30 14:31:02 -07:00
Makefile mm: per-thread vma caching 2014-04-07 16:35:53 -07:00
memblock.c ARM: 7993/1: mm/memblock: add memblock_get_current_limit 2014-03-12 00:16:56 +00:00
memcontrol.c Merge branch 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2014-04-03 13:05:42 -07:00
memory_hotplug.c mm/memory_hotplug.c: move register_memory_resource out of the lock_memory_hotplug 2014-01-23 16:36:52 -08:00
memory-failure.c Merge branch 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2014-04-03 13:05:42 -07:00
memory.c mm: add debugfs tunable for fault_around_order 2014-04-07 16:35:53 -07:00
mempolicy.c mm, mempolicy: remove per-process flag 2014-04-07 16:35:54 -07:00
mempool.c mempool: add unlikely and likely hints 2014-04-07 16:35:55 -07:00
migrate.c mm: fix swapops.h:131 bug if remap_file_pages raced migration 2014-03-20 22:09:09 -07:00
mincore.c mm + fs: prepare for non-page entries in page cache radix trees 2014-04-03 16:21:00 -07:00
mlock.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
mm_init.c mm: bring back /sys/kernel/mm 2014-01-27 21:02:39 -08:00
mmap.c mm: per-thread vma caching 2014-04-07 16:35:53 -07:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c mm: audit/fix non-modular users of module_init in core code 2014-01-23 16:36:52 -08:00
mmzone.c mm: numa: Change page last {nid,pid} into {cpu,pid} 2013-10-09 14:47:45 +02:00
mprotect.c mm: move mmu notifier call from change_protection to change_pmd_range 2014-04-07 16:35:50 -07:00
mremap.c mm: revert mremap pud_free anti-fix 2013-10-16 21:35:53 -07:00
msync.c
nobootmem.c mm/nobootmem.c: mark function as static 2014-04-03 16:21:02 -07:00
nommu.c mm: fix 'ERROR: do not initialise globals to 0 or NULL' and coding style 2014-04-07 16:35:55 -07:00
oom_kill.c mm, oom: base root bonus on current usage 2014-01-30 16:56:56 -08:00
page_alloc.c mm: exclude memoryless nodes from zone_reclaim 2014-04-07 16:35:50 -07:00
page_cgroup.c mm/page_cgroup.c: mark functions as static 2014-04-03 16:21:02 -07:00
page_io.c Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-block 2014-01-30 11:19:05 -08:00
page_isolation.c mm: memory-hotplug: enable memory hotplug to handle hugepage 2013-09-11 15:57:48 -07:00
page-writeback.c mm: __set_page_dirty_nobuffers() uses spin_lock_irqsave() instead of spin_lock_irq() 2014-02-06 13:48:51 -08:00
pagewalk.c mm/pagewalk.c: fix walk_page_range() access of wrong PTEs 2013-10-30 14:27:03 -07:00
percpu-km.c
percpu-vm.c
percpu.c percpu: renew the max_contig if we merge the head and previous block 2014-03-29 09:29:42 -04:00
pgtable-generic.c mm: fix TLB flush race between migration, and change_protection_range 2013-12-18 19:04:51 -08:00
process_vm_access.c mm/process_vm_access.c: mark function as static 2014-04-03 16:21:02 -07:00
quicklist.c
readahead.c mm/readahead.c: fix readahead failure for memoryless NUMA nodes and limit readahead pages 2014-04-03 16:21:05 -07:00
rmap.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2014-03-31 14:35:30 -07:00
shmem.c mm: implement ->map_pages for shmem/tmpfs 2014-04-07 16:35:53 -07:00
slab_common.c slab: fix wrong retval on kmem_cache_create_memcg error path 2014-01-29 16:22:40 -08:00
slab.c mm, mempolicy: remove per-process flag 2014-04-07 16:35:54 -07:00
slab.h memcg, slab: RCU protect memcg_params for root caches 2014-01-23 16:36:51 -08:00
slob.c mm/sl[aou]b: Move kmallocXXX functions to common code 2013-09-04 20:51:33 +03:00
slub.c mm, mempolicy: rename slab_node for clarity 2014-04-07 16:35:54 -07:00
sparse-vmemmap.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
sparse.c mm: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
swap_state.c swap: add a simple detector for inappropriate swapin readahead 2014-02-06 13:48:51 -08:00
swap.c mm: thrash detection-based file cache sizing 2014-04-03 16:21:01 -07:00
swapfile.c mm/swap: fix race on swap_info reuse between swapoff and swapon 2014-02-06 13:48:51 -08:00
truncate.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
util.c mm: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
vmacache.c mm: per-thread vma caching 2014-04-07 16:35:53 -07:00
vmalloc.c mm/vmalloc.c: enhance vm_map_ram() comment 2014-04-07 16:35:55 -07:00
vmpressure.c arm, pm, vmpressure: add missing slab.h includes 2014-02-03 13:24:01 -05:00
vmscan.c mm/vmscan: do not check compaction_ready on promoted zones 2014-04-07 16:35:50 -07:00
vmstat.c drop_caches: add some documentation and info message 2014-04-03 16:21:04 -07:00
workingset.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
zbud.c mm/zbud: fix some trivial typos in comments 2013-09-11 15:57:35 -07:00
zsmalloc.c zsmalloc: add copyright 2014-01-30 16:56:55 -08:00
zswap.c mm/zswap.c: change params from hidden to ro 2014-01-23 16:36:50 -08:00