linux-stable.git/kernel/cgroup/cpuset.c, branch v6.2

cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task

2023-02-06T20:18:36+00:00

set_cpus_allowed_ptr() will fail with -EINVAL if the requested
affinity mask is not a subset of the task_cpu_possible_mask() for the
task being updated. Consequently, on a heterogeneous system with cpusets
spanning the different CPU types, updates to the cgroup hierarchy can
silently fail to update task affinities when the effective affinity
mask for the cpuset is expanded.

For example, consider an arm64 system with 4 CPUs, where CPUs 2-3 are
the only cores capable of executing 32-bit tasks. Attaching a 32-bit
task to a cpuset containing CPUs 0-2 will correctly affine the task to
CPU 2. Extending the cpuset to CPUs 0-3, however, will fail to extend
the affinity mask of the 32-bit task because update_tasks_cpumask() will
pass the full 0-3 mask to set_cpus_allowed_ptr().

Extend update_tasks_cpumask() to take a temporary 'cpumask' paramater
and use it to mask the 'effective_cpus' mask with the possible mask for
each task being updated.

Fixes: 431c69fac05b ("cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()")
Signed-off-by: Will Deacon 
Acked-by: Waiman Long 
Signed-off-by: Tejun Heo

cgroup/cpuset: Don't filter offline CPUs in cpuset_cpus_allowed() for top cpuset tasks

2023-02-06T20:15:08+00:00

Since commit 8f9ea86fdf99 ("sched: Always preserve the user
requested cpumask"), relax_compatible_cpus_allowed_ptr() is calling
__sched_setaffinity() unconditionally. This helps to expose a bug in
the current cpuset hotplug code where the cpumasks of the tasks in
the top cpuset are not updated at all when some CPUs become online or
offline. It is likely caused by the fact that some of the tasks in the
top cpuset, like percpu kthreads, cannot have their cpu affinity changed.

One way to reproduce this as suggested by Peter is:
 - boot machine
 - offline all CPUs except one
 - taskset -p ffffffff $$
 - online all CPUs

Fix this by allowing cpuset_cpus_allowed() to return a wider mask that
includes offline CPUs for those tasks that are in the top cpuset. For
tasks not in the top cpuset, the old rule applies and only online CPUs
will be returned in the mask since hotplug events will update their
cpumasks accordingly.

Fixes: 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask")
Reported-by: Will Deacon 
Originally-from: Peter Zijlstra (Intel) 
Tested-by: Will Deacon 
Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo

cgroup/cpuset: Fix wrong check in update_parent_subparts_cpumask()

2023-01-31T22:14:02+00:00

It was found that the check to see if a partition could use up all
the cpus from the parent cpuset in update_parent_subparts_cpumask()
was incorrect. As a result, it is possible to leave parent with no
effective cpu left even if there are tasks in the parent cpuset. This
can lead to system panic as reported in [1].

Fix this probem by updating the check to fail the enabling the partition
if parent's effective_cpus is a subset of the child's cpus_allowed.

Also record the error code when an error happens in update_prstate()
and add a test case where parent partition and child have the same cpu
list and parent has task. Enabling partition in the child will fail in
this case.

[1] https://www.spinics.net/lists/cgroups/msg36254.html

Fixes: f0af1bfc27b5 ("cgroup/cpuset: Relax constraints to partition & cpus changes")
Cc: stable@vger.kernel.org # v6.1
Reported-by: Srinivas Pandruvada 
Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo

Merge tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-12-14T03:29:45+00:00

Pull MM updates from Andrew Morton:

 - More userfaultfs work from Peter Xu

 - Several convert-to-folios series from Sidhartha Kumar and Huang Ying

 - Some filemap cleanups from Vishal Moola

 - David Hildenbrand added the ability to selftest anon memory COW
   handling

 - Some cpuset simplifications from Liu Shixin

 - Addition of vmalloc tracing support by Uladzislau Rezki

 - Some pagecache folioifications and simplifications from Matthew
   Wilcox

 - A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use
   it

 - Miguel Ojeda contributed some cleanups for our use of the
   __no_sanitize_thread__ gcc keyword.

   This series should have been in the non-MM tree, my bad

 - Naoya Horiguchi improved the interaction between memory poisoning and
   memory section removal for huge pages

 - DAMON cleanups and tuneups from SeongJae Park

 - Tony Luck fixed the handling of COW faults against poisoned pages

 - Peter Xu utilized the PTE marker code for handling swapin errors

 - Hugh Dickins reworked compound page mapcount handling, simplifying it
   and making it more efficient

 - Removal of the autonuma savedwrite infrastructure from Nadav Amit and
   David Hildenbrand

 - zram support for multiple compression streams from Sergey Senozhatsky

 - David Hildenbrand reworked the GUP code's R/O long-term pinning so
   that drivers no longer need to use the FOLL_FORCE workaround which
   didn't work very well anyway

 - Mel Gorman altered the page allocator so that local IRQs can remnain
   enabled during per-cpu page allocations

 - Vishal Moola removed the try_to_release_page() wrapper

 - Stefan Roesch added some per-BDI sysfs tunables which are used to
   prevent network block devices from dirtying excessive amounts of
   pagecache

 - David Hildenbrand did some cleanup and repair work on KSM COW
   breaking

 - Nhat Pham and Johannes Weiner have implemented writeback in zswap's
   zsmalloc backend

 - Brian Foster has fixed a longstanding corner-case oddity in
   file[map]_write_and_wait_range()

 - sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
   Chen

 - Shiyang Ruan has done some work on fsdax, to make its reflink mode
   work better under xfstests. Better, but still not perfect

 - Christoph Hellwig has removed the .writepage() method from several
   filesystems. They only need .writepages()

 - Yosry Ahmed wrote a series which fixes the memcg reclaim target
   beancounting

 - David Hildenbrand has fixed some of our MM selftests for 32-bit
   machines

 - Many singleton patches, as usual

* tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (313 commits)
  mm/hugetlb: set head flag before setting compound_order in __prep_compound_gigantic_folio
  mm: mmu_gather: allow more than one batch of delayed rmaps
  mm: fix typo in struct pglist_data code comment
  kmsan: fix memcpy tests
  mm: add cond_resched() in swapin_walk_pmd_entry()
  mm: do not show fs mm pc for VM_LOCKONFAULT pages
  selftests/vm: ksm_functional_tests: fixes for 32bit
  selftests/vm: cow: fix compile warning on 32bit
  selftests/vm: madv_populate: fix missing MADV_POPULATE_(READ|WRITE) definitions
  mm/gup_test: fix PIN_LONGTERM_TEST_READ with highmem
  mm,thp,rmap: fix races between updates of subpages_mapcount
  mm: memcg: fix swapcached stat accounting
  mm: add nodes= arg to memory.reclaim
  mm: disable top-tier fallback to reclaim on proactive reclaim
  selftests: cgroup: make sure reclaim target memcg is unprotected
  selftests: cgroup: refactor proactive reclaim code to reclaim_until()
  mm: memcg: fix stale protection of reclaim target memcg
  mm/mmap: properly unaccount memory on mas_preallocate() failure
  omfs: remove ->writepage
  jfs: remove ->writepage
  ...

cgroup/cpuset: Improve cpuset_css_alloc() description

2022-11-22T21:11:47+00:00

Change the function argument in the description of cpuset_css_alloc()
from 'struct cgroup' -> 'struct cgroup_subsys_state'.  The change to the
argument type was introduced by commit eb95419b023a ("cgroup: pass
around cgroup_subsys_state instead of cgroup in subsystem methods").
Also, add more information to its description.

Signed-off-by: Kamalesh Babulal 
Acked-by: Waiman Long 
Acked-by: Joel Savitz 
Signed-off-by: Tejun Heo

cgroup/cpuset: Optimize cpuset_attach() on v2

2022-11-14T21:45:56+00:00

It was found that with the default hierarchy, enabling cpuset in the
child cgroups can trigger a cpuset_attach() call in each of the child
cgroups that have tasks with no change in effective cpus and mems. If
there are many processes in those child cgroups, it will burn quite a
lot of cpu cycles iterating all the tasks without doing useful work.

Optimizing this case by comparing between the old and new cpusets and
skip useless update if there is no change in effective cpus and mems.
Also mems_allowed are less likely to be changed than cpus_allowed. So
skip changing mm if there is no change in effective_mems and
CS_MEMORY_MIGRATE is not set.

By inserting some instrumentation code and running a simple command in
a container 200 times in a cgroup v2 system, it was found that all the
cpuset_attach() calls are skipped (401 times in total) as there was no
change in effective cpus and mems.

Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo

cgroup/cpuset: Skip spread flags update on v2

2022-11-14T21:45:51+00:00

Cpuset v2 has no spread flags to set. So we can skip spread
flags update if cpuset v2 is being used. Also change the name to
cpuset_update_task_spread_flags() to indicate that there are multiple
spread flags.

Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo

memory: move hotplug memory notifier priority to same file for easy sorting

2022-11-09T01:37:17+00:00

The priority of hotplug memory callback is defined in a different file. 
And there are some callers using numbers directly.  Collect them together
into include/linux/memory.h for easy reading.  This allows us to sort
their priorities more intuitively without additional comments.

Link: https://lkml.kernel.org/r/20220923033347.3935160-9-liushixin2@huawei.com
Signed-off-by: Liu Shixin 
Cc: Christoph Lameter 
Cc: David Hildenbrand 
Cc: Kefeng Wang 
Cc: Waiman Long 
Cc: zefan li 
Signed-off-by: Andrew Morton

cgroup/cpuset: use hotplug_memory_notifier() directly

2022-11-09T01:37:15+00:00

Patch series "mm: Use hotplug_memory_notifier() instead of
register_hotmemory_notifier()", v4.

Commit f02c69680088 ("include/linux/memory.h: implement
register_hotmemory_notifier()") introduced register_hotmemory_notifier()
to avoid a compile problem with gcc-4.4.4:

    When CONFIG_MEMORY_HOTPLUG=n, we don't want the memory-hotplug notifier
    handlers to be included in the .o files, for space reasons.
    
    The existing hotplug_memory_notifier() tries to handle this but testing
    with gcc-4.4.4 shows that it doesn't work - the hotplug functions are
    still present in the .o files.

Since commit 76ae847497bc52 ("Documentation: raise minimum supported
version of GCC to 5.1") has already updated the minimum gcc version to
5.1.  The previous problem mentioned in f02c69680088 does not exist.  So
we can now revert to use hotplug_memory_notifier() directly rather than
register_hotmemory_notifier().

In the last patch, we move all hotplug memory notifier priority to same
file for easy sorting.


This patch (of 8):

Commit 76ae847497bc52 ("Documentation: raise minimum supported version of
GCC to 5.1") updated the minimum gcc version to 5.1.  So the problem
mentioned in f02c69680088 ("include/linux/memory.h: implement
register_hotmemory_notifier()") no longer exist.  So we can now switch to
use hotplug_memory_notifier() directly rather than
register_hotmemory_notifier().

Link: https://lkml.kernel.org/r/20220923033347.3935160-1-liushixin2@huawei.com
Link: https://lkml.kernel.org/r/20220923033347.3935160-2-liushixin2@huawei.com
Signed-off-by: Liu Shixin 
Reviewed-by: David Hildenbrand 
Cc: Christoph Lameter 
Cc: Kefeng Wang 
Cc: Waiman Long 
Cc: zefan li 
Signed-off-by: Andrew Morton

cgroup/cpuset: remove unreachable code

2022-09-07T15:30:29+00:00

The function sched_partition_show cannot execute seq_puts, delete the
invalid code.

kernel/cgroup/cpuset.c:2849 sched_partition_show() warn: ignoring unreachable code.

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2087
Reported-by: Abaci Robot 
Signed-off-by: Jiapeng Chong 
Signed-off-by: Tejun Heo