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871 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Elena Reshetova
|
f0b89d3958 |
sched/core: Convert task_struct.stack_refcount to refcount_t
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable task_struct.stack_refcount is used as pure reference counter. Convert it to refcount_t and fix up the operations. ** Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the task_struct.stack_refcount it might make a difference in following places: - try_get_task_stack(): increment in refcount_inc_not_zero() only guarantees control dependency on success vs. fully ordered atomic counterpart - put_task_stack(): decrement in refcount_dec_and_test() only provides RELEASE ordering and control dependency on success vs. fully ordered atomic counterpart Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1547814450-18902-6-git-send-email-elena.reshetova@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Elena Reshetova
|
ec1d281923 |
sched/core: Convert task_struct.usage to refcount_t
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable task_struct.usage is used as pure reference counter. Convert it to refcount_t and fix up the operations. ** Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the task_struct.usage it might make a difference in following places: - put_task_struct(): decrement in refcount_dec_and_test() only provides RELEASE ordering and control dependency on success vs. fully ordered atomic counterpart Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1547814450-18902-5-git-send-email-elena.reshetova@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Elena Reshetova
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60d4de3ff7 |
sched/core: Convert signal_struct.sigcnt to refcount_t
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable signal_struct.sigcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. ** Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the signal_struct.sigcnt it might make a difference in following places: - put_signal_struct(): decrement in refcount_dec_and_test() only provides RELEASE ordering and control dependency on success vs. fully ordered atomic counterpart Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1547814450-18902-3-git-send-email-elena.reshetova@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Elena Reshetova
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d036bda7d0 |
sched/core: Convert sighand_struct.count to refcount_t
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable sighand_struct.count is used as pure reference counter. Convert it to refcount_t and fix up the operations. ** Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the sighand_struct.count it might make a difference in following places: - __cleanup_sighand: decrement in refcount_dec_and_test() only provides RELEASE ordering and control dependency on success vs. fully ordered atomic counterpart Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1547814450-18902-2-git-send-email-elena.reshetova@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Linus Torvalds
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a88cc8da02 |
Merge branch 'akpm' (patches from Andrew)
Merge misc fixes from Andrew Morton: "14 fixes" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: mm, page_alloc: do not wake kswapd with zone lock held hugetlbfs: revert "use i_mmap_rwsem for more pmd sharing synchronization" hugetlbfs: revert "Use i_mmap_rwsem to fix page fault/truncate race" mm: page_mapped: don't assume compound page is huge or THP mm/memory.c: initialise mmu_notifier_range correctly tools/vm/page_owner: use page_owner_sort in the use example kasan: fix krealloc handling for tag-based mode kasan: make tag based mode work with CONFIG_HARDENED_USERCOPY kasan, arm64: use ARCH_SLAB_MINALIGN instead of manual aligning mm, memcg: fix reclaim deadlock with writeback mm/usercopy.c: no check page span for stack objects slab: alien caches must not be initialized if the allocation of the alien cache failed fork, memcg: fix cached_stacks case zram: idle writeback fixes and cleanup |
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Shakeel Butt
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ba4a45746c |
fork, memcg: fix cached_stacks case
Commit |
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David Herrmann
|
7b55851367 |
fork: record start_time late
This changes the fork(2) syscall to record the process start_time after initializing the basic task structure but still before making the new process visible to user-space. Technically, we could record the start_time anytime during fork(2). But this might lead to scenarios where a start_time is recorded long before a process becomes visible to user-space. For instance, with userfaultfd(2) and TLS, user-space can delay the execution of fork(2) for an indefinite amount of time (and will, if this causes network access, or similar). By recording the start_time late, it much closer reflects the point in time where the process becomes live and can be observed by other processes. Lastly, this makes it much harder for user-space to predict and control the start_time they get assigned. Previously, user-space could fork a process and stall it in copy_thread_tls() before its pid is allocated, but after its start_time is recorded. This can be misused to later-on cycle through PIDs and resume the stalled fork(2) yielding a process that has the same pid and start_time as a process that existed before. This can be used to circumvent security systems that identify processes by their pid+start_time combination. Even though user-space was always aware that start_time recording is flaky (but several projects are known to still rely on start_time-based identification), changing the start_time to be recorded late will help mitigate existing attacks and make it much harder for user-space to control the start_time a process gets assigned. Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Tom Gundersen <teg@jklm.no> Signed-off-by: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Yi Wang
|
fb5bf31722 |
fork: fix some -Wmissing-prototypes warnings
We get a warning when building kernel with W=1:
kernel/fork.c:167:13: warning: no previous prototype for `arch_release_thread_stack' [-Wmissing-prototypes]
kernel/fork.c:779:13: warning: no previous prototype for `fork_init' [-Wmissing-prototypes]
Add the missing declaration in head file to fix this.
Also, remove arch_release_thread_stack() completely because no arch
seems to implement it since
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YueHaibing
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0f4991e8fd |
kernel/fork.c: mark 'stack_vm_area' with __maybe_unused
Fixes gcc '-Wunused-but-set-variable' warning when CONFIG_VMAP_STACK is not set: kernel/fork.c: In function 'dup_task_struct': kernel/fork.c:843:20: warning: variable 'stack_vm_area' set but not used [-Wunused-but-set-variable] Link: http://lkml.kernel.org/r/1545965190-2381-1-git-send-email-yuehaibing@huawei.com Signed-off-by: YueHaibing <yuehaibing@huawei.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Arun KS
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ca79b0c211 |
mm: convert totalram_pages and totalhigh_pages variables to atomic
totalram_pages and totalhigh_pages are made static inline function. Main motivation was that managed_page_count_lock handling was complicating things. It was discussed in length here, https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes better to remove the lock and convert variables to atomic, with preventing poteintial store-to-read tearing as a bonus. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org Signed-off-by: Arun KS <arunks@codeaurora.org> Suggested-by: Michal Hocko <mhocko@suse.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Arun KS
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3d6357de8a |
mm: reference totalram_pages and managed_pages once per function
Patch series "mm: convert totalram_pages, totalhigh_pages and managed pages to atomic", v5. This series converts totalram_pages, totalhigh_pages and zone->managed_pages to atomic variables. totalram_pages, zone->managed_pages and totalhigh_pages updates are protected by managed_page_count_lock, but readers never care about it. Convert these variables to atomic to avoid readers potentially seeing a store tear. Main motivation was that managed_page_count_lock handling was complicating things. It was discussed in length here, https://lore.kernel.org/patchwork/patch/995739/#1181785 It seemes better to remove the lock and convert variables to atomic. With the change, preventing poteintial store-to-read tearing comes as a bonus. This patch (of 4): This is in preparation to a later patch which converts totalram_pages and zone->managed_pages to atomic variables. Please note that re-reading the value might lead to a different value and as such it could lead to unexpected behavior. There are no known bugs as a result of the current code but it is better to prevent from them in principle. Link: http://lkml.kernel.org/r/1542090790-21750-2-git-send-email-arunks@codeaurora.org Signed-off-by: Arun KS <arunks@codeaurora.org> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Rik van Riel
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5eed6f1dff |
fork,memcg: fix crash in free_thread_stack on memcg charge fail
Commit |
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Linus Torvalds
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2d6bb6adb7 |
New gcc plugin: stackleak
- Introduces the stackleak gcc plugin ported from grsecurity by Alexander
Popov, with x86 and arm64 support.
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Merge tag 'stackleak-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull stackleak gcc plugin from Kees Cook:
"Please pull this new GCC plugin, stackleak, for v4.20-rc1. This plugin
was ported from grsecurity by Alexander Popov. It provides efficient
stack content poisoning at syscall exit. This creates a defense
against at least two classes of flaws:
- Uninitialized stack usage. (We continue to work on improving the
compiler to do this in other ways: e.g. unconditional zero init was
proposed to GCC and Clang, and more plugin work has started too).
- Stack content exposure. By greatly reducing the lifetime of valid
stack contents, exposures via either direct read bugs or unknown
cache side-channels become much more difficult to exploit. This
complements the existing buddy and heap poisoning options, but
provides the coverage for stacks.
The x86 hooks are included in this series (which have been reviewed by
Ingo, Dave Hansen, and Thomas Gleixner). The arm64 hooks have already
been merged through the arm64 tree (written by Laura Abbott and
reviewed by Mark Rutland and Will Deacon).
With VLAs having been removed this release, there is no need for
alloca() protection, so it has been removed from the plugin"
* tag 'stackleak-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
arm64: Drop unneeded stackleak_check_alloca()
stackleak: Allow runtime disabling of kernel stack erasing
doc: self-protection: Add information about STACKLEAK feature
fs/proc: Show STACKLEAK metrics in the /proc file system
lkdtm: Add a test for STACKLEAK
gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack
x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
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Johannes Weiner
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eb414681d5 |
psi: pressure stall information for CPU, memory, and IO
When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills. In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.
In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.
A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively. Stall states are aggregate versions of the per-task delay
accounting delays:
cpu: some tasks are runnable but not executing on a CPU
memory: tasks are reclaiming, or waiting for swapin or thrashing cache
io: tasks are waiting for io completions
These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit. They can also indicate when the system
is approaching lockup scenarios and OOMs.
To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states. Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime. A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).
[hannes@cmpxchg.org: doc fixlet, per Randy]
Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Roman Gushchin
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9b6f7e163c |
mm: rework memcg kernel stack accounting
If CONFIG_VMAP_STACK is set, kernel stacks are allocated using
__vmalloc_node_range() with __GFP_ACCOUNT. So kernel stack pages are
charged against corresponding memory cgroups on allocation and uncharged
on releasing them.
The problem is that we do cache kernel stacks in small per-cpu caches and
do reuse them for new tasks, which can belong to different memory cgroups.
Each stack page still holds a reference to the original cgroup, so the
cgroup can't be released until the vmap area is released.
To make this happen we need more than two subsequent exits without forks
in between on the current cpu, which makes it very unlikely to happen. As
a result, I saw a significant number of dying cgroups (in theory, up to 2
* number_of_cpu + number_of_tasks), which can't be released even by
significant memory pressure.
As a cgroup structure can take a significant amount of memory (first of
all, per-cpu data like memcg statistics), it leads to a noticeable waste
of memory.
Link: http://lkml.kernel.org/r/20180827162621.30187-1-guro@fb.com
Fixes:
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Nadav Amit
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1ed0cc5a01 |
mm: respect arch_dup_mmap() return value
Commit |
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Alexander Popov
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afaef01c00 |
x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
The STACKLEAK feature (initially developed by PaX Team) has the following benefits: 1. Reduces the information that can be revealed through kernel stack leak bugs. The idea of erasing the thread stack at the end of syscalls is similar to CONFIG_PAGE_POISONING and memzero_explicit() in kernel crypto, which all comply with FDP_RIP.2 (Full Residual Information Protection) of the Common Criteria standard. 2. Blocks some uninitialized stack variable attacks (e.g. CVE-2017-17712, CVE-2010-2963). That kind of bugs should be killed by improving C compilers in future, which might take a long time. This commit introduces the code filling the used part of the kernel stack with a poison value before returning to userspace. Full STACKLEAK feature also contains the gcc plugin which comes in a separate commit. The STACKLEAK feature is ported from grsecurity/PaX. More information at: https://grsecurity.net/ https://pax.grsecurity.net/ This code is modified from Brad Spengler/PaX Team's code in the last public patch of grsecurity/PaX based on our understanding of the code. Changes or omissions from the original code are ours and don't reflect the original grsecurity/PaX code. Performance impact: Hardware: Intel Core i7-4770, 16 GB RAM Test #1: building the Linux kernel on a single core 0.91% slowdown Test #2: hackbench -s 4096 -l 2000 -g 15 -f 25 -P 4.2% slowdown So the STACKLEAK description in Kconfig includes: "The tradeoff is the performance impact: on a single CPU system kernel compilation sees a 1% slowdown, other systems and workloads may vary and you are advised to test this feature on your expected workload before deploying it". Signed-off-by: Alexander Popov <alex.popov@linux.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> |
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Linus Torvalds
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cd9b44f907 |
Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton: - the rest of MM - procfs updates - various misc things - more y2038 fixes - get_maintainer updates - lib/ updates - checkpatch updates - various epoll updates - autofs updates - hfsplus - some reiserfs work - fatfs updates - signal.c cleanups - ipc/ updates * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (166 commits) ipc/util.c: update return value of ipc_getref from int to bool ipc/util.c: further variable name cleanups ipc: simplify ipc initialization ipc: get rid of ids->tables_initialized hack lib/rhashtable: guarantee initial hashtable allocation lib/rhashtable: simplify bucket_table_alloc() ipc: drop ipc_lock() ipc/util.c: correct comment in ipc_obtain_object_check ipc: rename ipcctl_pre_down_nolock() ipc/util.c: use ipc_rcu_putref() for failues in ipc_addid() ipc: reorganize initialization of kern_ipc_perm.seq ipc: compute kern_ipc_perm.id under the ipc lock init/Kconfig: remove EXPERT from CHECKPOINT_RESTORE fs/sysv/inode.c: use ktime_get_real_seconds() for superblock stamp adfs: use timespec64 for time conversion kernel/sysctl.c: fix typos in comments drivers/rapidio/devices/rio_mport_cdev.c: remove redundant pointer md fork: don't copy inconsistent signal handler state to child signal: make get_signal() return bool signal: make sigkill_pending() return bool ... |
||
Jann Horn
|
06e62a46bb |
fork: don't copy inconsistent signal handler state to child
Before this change, if a multithreaded process forks while one of its threads is changing a signal handler using sigaction(), the memcpy() in copy_sighand() can race with the struct assignment in do_sigaction(). It isn't clear whether this can cause corruption of the userspace signal handler pointer, but it definitely can cause inconsistency between different fields of struct sigaction. Take the appropriate spinlock to avoid this. I have tested that this patch prevents inconsistency between sa_sigaction and sa_flags, which is possible before this patch. Link: http://lkml.kernel.org/r/20180702145108.73189-1-jannh@google.com Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Rik van Riel <riel@redhat.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Kees Cook <keescook@chromium.org> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Dmitry Vyukov
|
a2e5144538 |
kernel/hung_task.c: allow to set checking interval separately from timeout
Currently task hung checking interval is equal to timeout, as the result hung is detected anywhere between timeout and 2*timeout. This is fine for most interactive environments, but this hurts automated testing setups (syzbot). In an automated setup we need to strictly order CPU lockup < RCU stall < workqueue lockup < task hung < silent loss, so that RCU stall is not detected as task hung and task hung is not detected as silent machine loss. The large variance in task hung detection timeout requires setting silent machine loss timeout to a very large value (e.g. if task hung is 3 mins, then silent loss need to be set to ~7 mins). The additional 3 minutes significantly reduce testing efficiency because usually we crash kernel within a minute, and this can add hours to bug localization process as it needs to do dozens of tests. Allow setting checking interval separately from timeout. This allows to set timeout to, say, 3 minutes, but checking interval to 10 secs. The interval is controlled via a new hung_task_check_interval_secs sysctl, similar to the existing hung_task_timeout_secs sysctl. The default value of 0 results in the current behavior: checking interval is equal to timeout. [akpm@linux-foundation.org: update hung_task_timeout_max's comment] Link: http://lkml.kernel.org/r/20180611111004.203513-1-dvyukov@google.com Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Andrew Morton
|
a670468f5e |
mm: zero out the vma in vma_init()
Rather than in vm_area_alloc(). To ensure that the various oddball stack-based vmas are in a good state. Some of the callers were zeroing them out, others were not. Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
|
0214f46b3a |
Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull core signal handling updates from Eric Biederman:
"It was observed that a periodic timer in combination with a
sufficiently expensive fork could prevent fork from every completing.
This contains the changes to remove the need for that restart.
This set of changes is split into several parts:
- The first part makes PIDTYPE_TGID a proper pid type instead
something only for very special cases. The part starts using
PIDTYPE_TGID enough so that in __send_signal where signals are
actually delivered we know if the signal is being sent to a a group
of processes or just a single process.
- With that prep work out of the way the logic in fork is modified so
that fork logically makes signals received while it is running
appear to be received after the fork completes"
* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (22 commits)
signal: Don't send signals to tasks that don't exist
signal: Don't restart fork when signals come in.
fork: Have new threads join on-going signal group stops
fork: Skip setting TIF_SIGPENDING in ptrace_init_task
signal: Add calculate_sigpending()
fork: Unconditionally exit if a fatal signal is pending
fork: Move and describe why the code examines PIDNS_ADDING
signal: Push pid type down into complete_signal.
signal: Push pid type down into __send_signal
signal: Push pid type down into send_signal
signal: Pass pid type into do_send_sig_info
signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task
signal: Pass pid type into group_send_sig_info
signal: Pass pid and pid type into send_sigqueue
posix-timers: Noralize good_sigevent
signal: Use PIDTYPE_TGID to clearly store where file signals will be sent
pid: Implement PIDTYPE_TGID
pids: Move the pgrp and session pid pointers from task_struct to signal_struct
kvm: Don't open code task_pid in kvm_vcpu_ioctl
pids: Compute task_tgid using signal->leader_pid
...
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Shakeel Butt
|
d46eb14b73 |
fs: fsnotify: account fsnotify metadata to kmemcg
Patch series "Directed kmem charging", v8. The Linux kernel's memory cgroup allows limiting the memory usage of the jobs running on the system to provide isolation between the jobs. All the kernel memory allocated in the context of the job and marked with __GFP_ACCOUNT will also be included in the memory usage and be limited by the job's limit. The kernel memory can only be charged to the memcg of the process in whose context kernel memory was allocated. However there are cases where the allocated kernel memory should be charged to the memcg different from the current processes's memcg. This patch series contains two such concrete use-cases i.e. fsnotify and buffer_head. The fsnotify event objects can consume a lot of system memory for large or unlimited queues if there is either no or slow listener. The events are allocated in the context of the event producer. However they should be charged to the event consumer. Similarly the buffer_head objects can be allocated in a memcg different from the memcg of the page for which buffer_head objects are being allocated. To solve this issue, this patch series introduces mechanism to charge kernel memory to a given memcg. In case of fsnotify events, the memcg of the consumer can be used for charging and for buffer_head, the memcg of the page can be charged. For directed charging, the caller can use the scope API memalloc_[un]use_memcg() to specify the memcg to charge for all the __GFP_ACCOUNT allocations within the scope. This patch (of 2): A lot of memory can be consumed by the events generated for the huge or unlimited queues if there is either no or slow listener. This can cause system level memory pressure or OOMs. So, it's better to account the fsnotify kmem caches to the memcg of the listener. However the listener can be in a different memcg than the memcg of the producer and these allocations happen in the context of the event producer. This patch introduces remote memcg charging API which the producer can use to charge the allocations to the memcg of the listener. There are seven fsnotify kmem caches and among them allocations from dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and inotify_inode_mark_cachep happens in the context of syscall from the listener. So, SLAB_ACCOUNT is enough for these caches. The objects from fsnotify_mark_connector_cachep are not accounted as they are small compared to the notification mark or events and it is unclear whom to account connector to since it is shared by all events attached to the inode. The allocations from the event caches happen in the context of the event producer. For such caches we will need to remote charge the allocations to the listener's memcg. Thus we save the memcg reference in the fsnotify_group structure of the listener. This patch has also moved the members of fsnotify_group to keep the size same, at least for 64 bit build, even with additional member by filling the holes. [shakeelb@google.com: use GFP_KERNEL_ACCOUNT rather than open-coding it] Link: http://lkml.kernel.org/r/20180702215439.211597-1-shakeelb@google.com Link: http://lkml.kernel.org/r/20180627191250.209150-2-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Greg Thelen <gthelen@google.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Roman Gushchin <guro@fb.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
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73ba2fb33c |
for-4.19/block-20180812
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Merge tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block
Pull block updates from Jens Axboe:
"First pull request for this merge window, there will also be a
followup request with some stragglers.
This pull request contains:
- Fix for a thundering heard issue in the wbt block code (Anchal
Agarwal)
- A few NVMe pull requests:
* Improved tracepoints (Keith)
* Larger inline data support for RDMA (Steve Wise)
* RDMA setup/teardown fixes (Sagi)
* Effects log suppor for NVMe target (Chaitanya Kulkarni)
* Buffered IO suppor for NVMe target (Chaitanya Kulkarni)
* TP4004 (ANA) support (Christoph)
* Various NVMe fixes
- Block io-latency controller support. Much needed support for
properly containing block devices. (Josef)
- Series improving how we handle sense information on the stack
(Kees)
- Lightnvm fixes and updates/improvements (Mathias/Javier et al)
- Zoned device support for null_blk (Matias)
- AIX partition fixes (Mauricio Faria de Oliveira)
- DIF checksum code made generic (Max Gurtovoy)
- Add support for discard in iostats (Michael Callahan / Tejun)
- Set of updates for BFQ (Paolo)
- Removal of async write support for bsg (Christoph)
- Bio page dirtying and clone fixups (Christoph)
- Set of bcache fix/changes (via Coly)
- Series improving blk-mq queue setup/teardown speed (Ming)
- Series improving merging performance on blk-mq (Ming)
- Lots of other fixes and cleanups from a slew of folks"
* tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block: (190 commits)
blkcg: Make blkg_root_lookup() work for queues in bypass mode
bcache: fix error setting writeback_rate through sysfs interface
null_blk: add lock drop/acquire annotation
Blk-throttle: reduce tail io latency when iops limit is enforced
block: paride: pd: mark expected switch fall-throughs
block: Ensure that a request queue is dissociated from the cgroup controller
block: Introduce blk_exit_queue()
blkcg: Introduce blkg_root_lookup()
block: Remove two superfluous #include directives
blk-mq: count the hctx as active before allocating tag
block: bvec_nr_vecs() returns value for wrong slab
bcache: trivial - remove tailing backslash in macro BTREE_FLAG
bcache: make the pr_err statement used for ENOENT only in sysfs_attatch section
bcache: set max writeback rate when I/O request is idle
bcache: add code comments for bset.c
bcache: fix mistaken comments in request.c
bcache: fix mistaken code comments in bcache.h
bcache: add a comment in super.c
bcache: avoid unncessary cache prefetch bch_btree_node_get()
bcache: display rate debug parameters to 0 when writeback is not running
...
|
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Linus Torvalds
|
203b4fc903 |
Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Thomas Gleixner: - Make lazy TLB mode even lazier to avoid pointless switch_mm() operations, which reduces CPU load by 1-2% for memcache workloads - Small cleanups and improvements all over the place * 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm: Remove redundant check for kmem_cache_create() arm/asm/tlb.h: Fix build error implicit func declaration x86/mm/tlb: Make clear_asid_other() static x86/mm/tlb: Skip atomic operations for 'init_mm' in switch_mm_irqs_off() x86/mm/tlb: Always use lazy TLB mode x86/mm/tlb: Only send page table free TLB flush to lazy TLB CPUs x86/mm/tlb: Make lazy TLB mode lazier x86/mm/tlb: Restructure switch_mm_irqs_off() x86/mm/tlb: Leave lazy TLB mode at page table free time mm: Allocate the mm_cpumask (mm->cpu_bitmap[]) dynamically based on nr_cpu_ids x86/mm: Add TLB purge to free pmd/pte page interfaces ioremap: Update pgtable free interfaces with addr x86/mm: Disable ioremap free page handling on x86-PAE |
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Eric W. Biederman
|
c3ad2c3b02 |
signal: Don't restart fork when signals come in.
Wen Yang <wen.yang99@zte.com.cn> and majiang <ma.jiang@zte.com.cn>
report that a periodic signal received during fork can cause fork to
continually restart preventing an application from making progress.
The code was being overly pessimistic. Fork needs to guarantee that a
signal sent to multiple processes is logically delivered before the
fork and just to the forking process or logically delivered after the
fork to both the forking process and it's newly spawned child. For
signals like periodic timers that are always delivered to a single
process fork can safely complete and let them appear to logically
delivered after the fork().
While examining this issue I also discovered that fork today will miss
signals delivered to multiple processes during the fork and handled by
another thread. Similarly the current code will also miss blocked
signals that are delivered to multiple process, as those signals will
not appear pending during fork.
Add a list of each thread that is currently forking, and keep on that
list a signal set that records all of the signals sent to multiple
processes. When fork completes initialize the new processes
shared_pending signal set with it. The calculate_sigpending function
will see those signals and set TIF_SIGPENDING causing the new task to
take the slow path to userspace to handle those signals. Making it
appear as if those signals were received immediately after the fork.
It is not possible to send real time signals to multiple processes and
exceptions don't go to multiple processes, which means that that are
no signals sent to multiple processes that require siginfo. This
means it is safe to not bother collecting siginfo on signals sent
during fork.
The sigaction of a child of fork is initially the same as the
sigaction of the parent process. So a signal the parent ignores the
child will also initially ignore. Therefore it is safe to ignore
signals sent to multiple processes and ignored by the forking process.
Signals sent to only a single process or only a single thread and delivered
during fork are treated as if they are received after the fork, and generally
not dealt with. They won't cause any problems.
V2: Added removal from the multiprocess list on failure.
V3: Use -ERESTARTNOINTR directly
V4: - Don't queue both SIGCONT and SIGSTOP
- Initialize signal_struct.multiprocess in init_task
- Move setting of shared_pending to before the new task
is visible to signals. This prevents signals from comming
in before shared_pending.signal is set to delayed.signal
and being lost.
V5: - rework list add and delete to account for idle threads
v6: - Use sigdelsetmask when removing stop signals
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200447
Reported-by: Wen Yang <wen.yang99@zte.com.cn> and
Reported-by: majiang <ma.jiang@zte.com.cn>
Fixes:
|
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Jens Axboe
|
05b9ba4b55 |
Linux 4.18-rc6
-----BEGIN PGP SIGNATURE----- iQFSBAABCAA8FiEEq68RxlopcLEwq+PEeb4+QwBBGIYFAltU8z0eHHRvcnZhbGRz QGxpbnV4LWZvdW5kYXRpb24ub3JnAAoJEHm+PkMAQRiG5X8H/2fJr7m3k242+t76 sitwvx1eoPqTgryW59dRKm9IuXAGA+AjauvHzaz1QxomeQa50JghGWefD0eiJfkA 1AphQ/24EOiAbbVk084dAI/C2p122dE4D5Fy7CrfLnuouyrbFaZI5STbnrRct7sR 9deeYW0GDHO1Uenp4WDCj0baaqJqaevZ+7GG09DnWpya2nQtSkGBjqn6GpYmrfOU mqFuxAX8mEOW6cwK16y/vYtnVjuuMAiZ63/OJ8AQ6d6ArGLwAsdn7f8Fn4I4tEr2 L0d3CRLUyegms4++Dmlu05k64buQu46WlPhjCZc5/Ts4kjrNxBuHejj2/jeSnUSt vJJlibI= =42a5 -----END PGP SIGNATURE----- Merge tag 'v4.18-rc6' into for-4.19/block2 Pull in 4.18-rc6 to get the NVMe core AEN change to avoid a merge conflict down the line. Signed-of-by: Jens Axboe <axboe@kernel.dk> |
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Eric W. Biederman
|
924de3b8c9 |
fork: Have new threads join on-going signal group stops
There are only two signals that are delivered to every member of a
signal group: SIGSTOP and SIGKILL. Signal delivery requires every
signal appear to be delivered either before or after a clone syscall.
SIGKILL terminates the clone so does not need to be considered. Which
leaves only SIGSTOP that needs to be considered when creating new
threads.
Today in the event of a group stop TIF_SIGPENDING will get set and the
fork will restart ensuring the fork syscall participates in the group
stop.
A fork (especially of a process with a lot of memory) is one of the
most expensive system so we really only want to restart a fork when
necessary.
It is easy so check to see if a SIGSTOP is ongoing and have the new
thread join it immediate after the clone completes. Making it appear
the clone completed happened just before the SIGSTOP.
The calculate_sigpending function will see the bits set in jobctl and
set TIF_SIGPENDING to ensure the new task takes the slow path to userspace.
V2: The call to task_join_group_stop was moved before the new task is
added to the thread group list. This should not matter as
sighand->siglock is held over both the addition of the threads,
the call to task_join_group_stop and do_signal_stop. But the change
is trivial and it is one less thing to worry about when reading
the code.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
|
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Josef Bacik
|
2c323017e3 |
blk-cgroup: clear the throttle queue on fork
We were hitting a panic in production where we put too many times on the request queue. This is because we'd get the throttle_queue of the parent if we fork()'ed while we needed to be throttled, but we didn't have a reference on it. Instead just clear these flags on fork so the child doesn't pay for the sins of its father. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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Kirill A. Shutemov
|
027232da7c |
mm: introduce vma_init()
Not all VMAs allocated with vm_area_alloc(). Some of them allocated on stack or in data segment. The new helper can be use to initialize VMA properly regardless where it was allocated. Link: http://lkml.kernel.org/r/20180724121139.62570-2-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
||
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Eric W. Biederman
|
7673bf553b |
fork: Unconditionally exit if a fatal signal is pending
In practice this does not change anything as testing for fatal_signal_pending and exiting for with an error code duplicates the work of the next clause which recalculates pending signals and then exits fork if any are pending. In both cases the pending signal will trigger the slow path when existing to userspace, and the fatal signal will cause do_exit to be called. The advantage of making this a separate test is that it makes it clear processing the fatal signal will terminate the fork, and it allows the rest of the signal logic to be updated without fear that this important case will be lost. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
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Eric W. Biederman
|
4ca1d3ee46 |
fork: Move and describe why the code examines PIDNS_ADDING
Normally this would be something that would be handled by handling signals that are sent to a group of processes but in this case the forking process is not a member of the group being signaled. Thus special code is needed to prevent a race with pid namespaces exiting, and fork adding new processes within them. Move this test up before the signal restart just in case signals are also pending. Fatal conditions should take presedence over restarts. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
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Linus Torvalds
|
490fc05386 |
mm: make vm_area_alloc() initialize core fields
Like vm_area_dup(), it initializes the anon_vma_chain head, and the basic mm pointer. The rest of the fields end up being different for different users, although the plan is to also initialize the 'vm_ops' field to a dummy entry. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
|
95faf6992d |
mm: make vm_area_dup() actually copy the old vma data
.. and re-initialize th eanon_vma_chain head. This removes some boiler-plate from the users, and also makes it clear why it didn't need use the 'zalloc()' version. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
|
3928d4f5ee |
mm: use helper functions for allocating and freeing vm_area structs
The vm_area_struct is one of the most fundamental memory management
objects, but the management of it is entirely open-coded evertwhere,
ranging from allocation and freeing (using kmem_cache_[z]alloc and
kmem_cache_free) to initializing all the fields.
We want to unify this in order to end up having some unified
initialization of the vmas, and the first step to this is to at least
have basic allocation functions.
Right now those functions are literally just wrappers around the
kmem_cache_*() calls. This is a purely mechanical conversion:
# new vma:
kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL) -> vm_area_alloc()
# copy old vma
kmem_cache_alloc(vm_area_cachep, GFP_KERNEL) -> vm_area_dup(old)
# free vma
kmem_cache_free(vm_area_cachep, vma) -> vm_area_free(vma)
to the point where the old vma passed in to the vm_area_dup() function
isn't even used yet (because I've left all the old manual initialization
alone).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
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Eric W. Biederman
|
6883f81aac |
pid: Implement PIDTYPE_TGID
Everywhere except in the pid array we distinguish between a tasks pid and a tasks tgid (thread group id). Even in the enumeration we want that distinction sometimes so we have added __PIDTYPE_TGID. With leader_pid we almost have an implementation of PIDTYPE_TGID in struct signal_struct. Add PIDTYPE_TGID as a first class member of the pid_type enumeration and into the pids array. Then remove the __PIDTYPE_TGID special case and the leader_pid in signal_struct. The net size increase is just an extra pointer added to struct pid and an extra pair of pointers of an hlist_node added to task_struct. The effect on code maintenance is the removal of a number of special cases today and the potential to remove many more special cases as PIDTYPE_TGID gets used to it's fullest. The long term potential is allowing zombie thread group leaders to exit, which will remove a lot more special cases in the code. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
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|
Eric W. Biederman
|
2c4704756c |
pids: Move the pgrp and session pid pointers from task_struct to signal_struct
To access these fields the code always has to go to group leader so going to signal struct is no loss and is actually a fundamental simplification. This saves a little bit of memory by only allocating the pid pointer array once instead of once for every thread, and even better this removes a few potential races caused by the fact that group_leader can be changed by de_thread, while signal_struct can not. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
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|
Rik van Riel
|
c1a2f7f0c0 |
mm: Allocate the mm_cpumask (mm->cpu_bitmap[]) dynamically based on nr_cpu_ids
The mm_struct always contains a cpumask bitmap, regardless of CONFIG_CPUMASK_OFFSTACK. That means the first step can be to simplify things, and simply have one bitmask at the end of the mm_struct for the mm_cpumask. This does necessitate moving everything else in mm_struct into an anonymous sub-structure, which can be randomized when struct randomization is enabled. The second step is to determine the correct size for the mm_struct slab object from the size of the mm_struct (excluding the CPU bitmap) and the size the cpumask. For init_mm we can simply allocate the maximum size this kernel is compiled for, since we only have one init_mm in the system, anyway. Pointer magic by Mike Galbraith, to evade -Wstringop-overflow getting confused by the dynamically sized array. Tested-by: Song Liu <songliubraving@fb.com> Signed-off-by: Rik van Riel <riel@surriel.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Rik van Riel <riel@surriel.com> Acked-by: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kernel-team@fb.com Cc: luto@kernel.org Link: http://lkml.kernel.org/r/20180716190337.26133-2-riel@surriel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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Tetsuo Handa
|
655c79bb40 |
mm: check for SIGKILL inside dup_mmap() loop
As a theoretical problem, dup_mmap() of an mm_struct with 60000+ vmas can loop while potentially allocating memory, with mm->mmap_sem held for write by current thread. This is bad if current thread was selected as an OOM victim, for current thread will continue allocations using memory reserves while OOM reaper is unable to reclaim memory. As an actually observable problem, it is not difficult to make OOM reaper unable to reclaim memory if the OOM victim is blocked at i_mmap_lock_write() in this loop. Unfortunately, since nobody can explain whether it is safe to use killable wait there, let's check for SIGKILL before trying to allocate memory. Even without an OOM event, there is no point with continuing the loop from the beginning if current thread is killed. I tested with debug printk(). This patch should be safe because we already fail if security_vm_enough_memory_mm() or kmem_cache_alloc(GFP_KERNEL) fails and exit_mmap() handles it. ***** Aborting dup_mmap() due to SIGKILL ***** ***** Aborting dup_mmap() due to SIGKILL ***** ***** Aborting dup_mmap() due to SIGKILL ***** ***** Aborting dup_mmap() due to SIGKILL ***** ***** Aborting exit_mmap() due to NULL mmap ***** [akpm@linux-foundation.org: add comment] Link: http://lkml.kernel.org/r/201804071938.CDE04681.SOFVQJFtMHOOLF@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Rik van Riel <riel@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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|
Linus Torvalds
|
050e9baa9d |
Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables
The changes to automatically test for working stack protector compiler support in the Kconfig files removed the special STACKPROTECTOR_AUTO option that picked the strongest stack protector that the compiler supported. That was all a nice cleanup - it makes no sense to have the AUTO case now that the Kconfig phase can just determine the compiler support directly. HOWEVER. It also meant that doing "make oldconfig" would now _disable_ the strong stackprotector if you had AUTO enabled, because in a legacy config file, the sane stack protector configuration would look like CONFIG_HAVE_CC_STACKPROTECTOR=y # CONFIG_CC_STACKPROTECTOR_NONE is not set # CONFIG_CC_STACKPROTECTOR_REGULAR is not set # CONFIG_CC_STACKPROTECTOR_STRONG is not set CONFIG_CC_STACKPROTECTOR_AUTO=y and when you ran this through "make oldconfig" with the Kbuild changes, it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version used to be disabled (because it was really enabled by AUTO), and would disable it in the new config, resulting in: CONFIG_HAVE_CC_STACKPROTECTOR=y CONFIG_CC_HAS_STACKPROTECTOR_NONE=y CONFIG_CC_STACKPROTECTOR=y # CONFIG_CC_STACKPROTECTOR_STRONG is not set CONFIG_CC_HAS_SANE_STACKPROTECTOR=y That's dangerously subtle - people could suddenly find themselves with the weaker stack protector setup without even realizing. The solution here is to just rename not just the old RECULAR stack protector option, but also the strong one. This does that by just removing the CC_ prefix entirely for the user choices, because it really is not about the compiler support (the compiler support now instead automatially impacts _visibility_ of the options to users). This results in "make oldconfig" actually asking the user for their choice, so that we don't have any silent subtle security model changes. The end result would generally look like this: CONFIG_HAVE_CC_STACKPROTECTOR=y CONFIG_CC_HAS_STACKPROTECTOR_NONE=y CONFIG_STACKPROTECTOR=y CONFIG_STACKPROTECTOR_STRONG=y CONFIG_CC_HAS_SANE_STACKPROTECTOR=y where the "CC_" versions really are about internal compiler infrastructure, not the user selections. Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Linus Torvalds
|
d82991a868 |
Merge branch 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull restartable sequence support from Thomas Gleixner: "The restartable sequences syscall (finally): After a lot of back and forth discussion and massive delays caused by the speculative distraction of maintainers, the core set of restartable sequences has finally reached a consensus. It comes with the basic non disputed core implementation along with support for arm, powerpc and x86 and a full set of selftests It was exposed to linux-next earlier this week, so it does not fully comply with the merge window requirements, but there is really no point to drag it out for yet another cycle" * 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rseq/selftests: Provide Makefile, scripts, gitignore rseq/selftests: Provide parametrized tests rseq/selftests: Provide basic percpu ops test rseq/selftests: Provide basic test rseq/selftests: Provide rseq library selftests/lib.mk: Introduce OVERRIDE_TARGETS powerpc: Wire up restartable sequences system call powerpc: Add syscall detection for restartable sequences powerpc: Add support for restartable sequences x86: Wire up restartable sequence system call x86: Add support for restartable sequences arm: Wire up restartable sequences system call arm: Add syscall detection for restartable sequences arm: Add restartable sequences support rseq: Introduce restartable sequences system call uapi/headers: Provide types_32_64.h |
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Yang Shi
|
88aa7cc688 |
mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct
mmap_sem is on the hot path of kernel, and it very contended, but it is
abused too. It is used to protect arg_start|end and evn_start|end when
reading /proc/$PID/cmdline and /proc/$PID/environ, but it doesn't make
sense since those proc files just expect to read 4 values atomically and
not related to VM, they could be set to arbitrary values by C/R.
And, the mmap_sem contention may cause unexpected issue like below:
INFO: task ps:14018 blocked for more than 120 seconds.
Tainted: G E 4.9.79-009.ali3000.alios7.x86_64 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
message.
ps D 0 14018 1 0x00000004
Call Trace:
schedule+0x36/0x80
rwsem_down_read_failed+0xf0/0x150
call_rwsem_down_read_failed+0x18/0x30
down_read+0x20/0x40
proc_pid_cmdline_read+0xd9/0x4e0
__vfs_read+0x37/0x150
vfs_read+0x96/0x130
SyS_read+0x55/0xc0
entry_SYSCALL_64_fastpath+0x1a/0xc5
Both Alexey Dobriyan and Michal Hocko suggested to use dedicated lock
for them to mitigate the abuse of mmap_sem.
So, introduce a new spinlock in mm_struct to protect the concurrent
access to arg_start|end, env_start|end and others, as well as replace
write map_sem to read to protect the race condition between prctl and
sys_brk which might break check_data_rlimit(), and makes prctl more
friendly to other VM operations.
This patch just eliminates the abuse of mmap_sem, but it can't resolve
the above hung task warning completely since the later
access_remote_vm() call needs acquire mmap_sem. The mmap_sem
scalability issue will be solved in the future.
[yang.shi@linux.alibaba.com: add comment about mmap_sem and arg_lock]
Link: http://lkml.kernel.org/r/1524077799-80690-1-git-send-email-yang.shi@linux.alibaba.com
Link: http://lkml.kernel.org/r/1523730291-109696-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Linus Torvalds
|
8b5c6a3a49 |
audit/stable-4.18 PR 20180605
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Mathieu Desnoyers
|
d7822b1e24 |
rseq: Introduce restartable sequences system call
Expose a new system call allowing each thread to register one userspace memory area to be used as an ABI between kernel and user-space for two purposes: user-space restartable sequences and quick access to read the current CPU number value from user-space. * Restartable sequences (per-cpu atomics) Restartables sequences allow user-space to perform update operations on per-cpu data without requiring heavy-weight atomic operations. The restartable critical sections (percpu atomics) work has been started by Paul Turner and Andrew Hunter. It lets the kernel handle restart of critical sections. [1] [2] The re-implementation proposed here brings a few simplifications to the ABI which facilitates porting to other architectures and speeds up the user-space fast path. Here are benchmarks of various rseq use-cases. Test hardware: arm32: ARMv7 Processor rev 4 (v7l) "Cubietruck", 2-core x86-64: Intel E5-2630 v3@2.40GHz, 16-core, hyperthreading The following benchmarks were all performed on a single thread. * Per-CPU statistic counter increment getcpu+atomic (ns/op) rseq (ns/op) speedup arm32: 344.0 31.4 11.0 x86-64: 15.3 2.0 7.7 * LTTng-UST: write event 32-bit header, 32-bit payload into tracer per-cpu buffer getcpu+atomic (ns/op) rseq (ns/op) speedup arm32: 2502.0 2250.0 1.1 x86-64: 117.4 98.0 1.2 * liburcu percpu: lock-unlock pair, dereference, read/compare word getcpu+atomic (ns/op) rseq (ns/op) speedup arm32: 751.0 128.5 5.8 x86-64: 53.4 28.6 1.9 * jemalloc memory allocator adapted to use rseq Using rseq with per-cpu memory pools in jemalloc at Facebook (based on rseq 2016 implementation): The production workload response-time has 1-2% gain avg. latency, and the P99 overall latency drops by 2-3%. * Reading the current CPU number Speeding up reading the current CPU number on which the caller thread is running is done by keeping the current CPU number up do date within the cpu_id field of the memory area registered by the thread. This is done by making scheduler preemption set the TIF_NOTIFY_RESUME flag on the current thread. Upon return to user-space, a notify-resume handler updates the current CPU value within the registered user-space memory area. User-space can then read the current CPU number directly from memory. Keeping the current cpu id in a memory area shared between kernel and user-space is an improvement over current mechanisms available to read the current CPU number, which has the following benefits over alternative approaches: - 35x speedup on ARM vs system call through glibc - 20x speedup on x86 compared to calling glibc, which calls vdso executing a "lsl" instruction, - 14x speedup on x86 compared to inlined "lsl" instruction, - Unlike vdso approaches, this cpu_id value can be read from an inline assembly, which makes it a useful building block for restartable sequences. - The approach of reading the cpu id through memory mapping shared between kernel and user-space is portable (e.g. ARM), which is not the case for the lsl-based x86 vdso. On x86, yet another possible approach would be to use the gs segment selector to point to user-space per-cpu data. This approach performs similarly to the cpu id cache, but it has two disadvantages: it is not portable, and it is incompatible with existing applications already using the gs segment selector for other purposes. Benchmarking various approaches for reading the current CPU number: ARMv7 Processor rev 4 (v7l) Machine model: Cubietruck - Baseline (empty loop): 8.4 ns - Read CPU from rseq cpu_id: 16.7 ns - Read CPU from rseq cpu_id (lazy register): 19.8 ns - glibc 2.19-0ubuntu6.6 getcpu: 301.8 ns - getcpu system call: 234.9 ns x86-64 Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz: - Baseline (empty loop): 0.8 ns - Read CPU from rseq cpu_id: 0.8 ns - Read CPU from rseq cpu_id (lazy register): 0.8 ns - Read using gs segment selector: 0.8 ns - "lsl" inline assembly: 13.0 ns - glibc 2.19-0ubuntu6 getcpu: 16.6 ns - getcpu system call: 53.9 ns - Speed (benchmark taken on v8 of patchset) Running 10 runs of hackbench -l 100000 seems to indicate, contrary to expectations, that enabling CONFIG_RSEQ slightly accelerates the scheduler: Configuration: 2 sockets * 8-core Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz (directly on hardware, hyperthreading disabled in BIOS, energy saving disabled in BIOS, turboboost disabled in BIOS, cpuidle.off=1 kernel parameter), with a Linux v4.6 defconfig+localyesconfig, restartable sequences series applied. * CONFIG_RSEQ=n avg.: 41.37 s std.dev.: 0.36 s * CONFIG_RSEQ=y avg.: 40.46 s std.dev.: 0.33 s - Size On x86-64, between CONFIG_RSEQ=n/y, the text size increase of vmlinux is 567 bytes, and the data size increase of vmlinux is 5696 bytes. [1] https://lwn.net/Articles/650333/ [2] http://www.linuxplumbersconf.org/2013/ocw/system/presentations/1695/original/LPC%20-%20PerCpu%20Atomics.pdf Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Joel Fernandes <joelaf@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Watson <davejwatson@fb.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: "H . Peter Anvin" <hpa@zytor.com> Cc: Chris Lameter <cl@linux.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Andrew Hunter <ahh@google.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> Cc: Paul Turner <pjt@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ben Maurer <bmaurer@fb.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-api@vger.kernel.org Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20151027235635.16059.11630.stgit@pjt-glaptop.roam.corp.google.com Link: http://lkml.kernel.org/r/20150624222609.6116.86035.stgit@kitami.mtv.corp.google.com Link: https://lkml.kernel.org/r/20180602124408.8430-3-mathieu.desnoyers@efficios.com |
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Richard Guy Briggs
|
c0b0ae8a87 |
audit: use inline function to set audit context
Recognizing that the audit context is an internal audit value, use an access function to set the audit context pointer for the task rather than reaching directly into the task struct to set it. Signed-off-by: Richard Guy Briggs <rgb@redhat.com> [PM: merge fuzz in audit.h] Signed-off-by: Paul Moore <paul@paul-moore.com> |
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Kees Cook
|
e01e80634e |
fork: unconditionally clear stack on fork
One of the classes of kernel stack content leaks[1] is exposing the contents of prior heap or stack contents when a new process stack is allocated. Normally, those stacks are not zeroed, and the old contents remain in place. In the face of stack content exposure flaws, those contents can leak to userspace. Fixing this will make the kernel no longer vulnerable to these flaws, as the stack will be wiped each time a stack is assigned to a new process. There's not a meaningful change in runtime performance; it almost looks like it provides a benefit. Performing back-to-back kernel builds before: Run times: 157.86 157.09 158.90 160.94 160.80 Mean: 159.12 Std Dev: 1.54 and after: Run times: 159.31 157.34 156.71 158.15 160.81 Mean: 158.46 Std Dev: 1.46 Instead of making this a build or runtime config, Andy Lutomirski recommended this just be enabled by default. [1] A noisy search for many kinds of stack content leaks can be seen here: https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=linux+kernel+stack+leak I did some more with perf and cycle counts on running 100,000 execs of /bin/true. before: Cycles: 218858861551 218853036130 214727610969 227656844122 224980542841 Mean: 221015379122.60 Std Dev: 4662486552.47 after: Cycles: 213868945060 213119275204 211820169456 224426673259 225489986348 Mean: 217745009865.40 Std Dev: 5935559279.99 It continues to look like it's faster, though the deviation is rather wide, but I'm not sure what I could do that would be less noisy. I'm open to ideas! Link: http://lkml.kernel.org/r/20180221021659.GA37073@beast Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Laura Abbott <labbott@redhat.com> Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mark Rutland
|
3eda69c92d |
kernel/fork.c: detect early free of a live mm
KASAN splats indicate that in some cases we free a live mm, then continue to access it, with potentially disastrous results. This is likely due to a mismatched mmdrop() somewhere in the kernel, but so far the culprit remains elusive. Let's have __mmdrop() verify that the mm isn't live for the current task, similar to the existing check for init_mm. This way, we can catch this class of issue earlier, and without requiring KASAN. Currently, idle_task_exit() leaves active_mm stale after it switches to init_mm. This isn't harmful, but will trigger the new assertions, so we must adjust idle_task_exit() to update active_mm. Link: http://lkml.kernel.org/r/20180312140103.19235-1-mark.rutland@arm.com Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Dominik Brodowski
|
9b32105ec6 |
kernel: add ksys_unshare() helper; remove in-kernel calls to sys_unshare()
Using this helper allows us to avoid the in-kernel calls to the sys_unshare() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_unshare(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> |
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Dominik Brodowski
|
2de0db992d |
mm: use do_futex() instead of sys_futex() in mm_release()
sys_futex() is a wrapper to do_futex() which does not modify any values here: - uaddr, val and val3 are kept the same - op is masked with FUTEX_CMD_MASK, but is always set to FUTEX_WAKE. Therefore, val2 is always 0. - as utime is set to NULL, *timeout is NULL This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Darren Hart <dvhart@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> |
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Andrew Morton
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d34bc48f82 |
include/linux/sched/mm.h: re-inline mmdrop()
As Peter points out, Doing a CALL+RET for just the decrement is a bit silly.
Fixes:
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