diff options
| author | Chen Yu <[email protected]> | 2025-07-04 13:56:20 +0000 |
|---|---|---|
| committer | Andrew Morton <[email protected]> | 2025-07-10 04:07:56 +0000 |
| commit | db6cc3f4ac2e6cdc898fc9cbc8b32ae1bf56bdad (patch) | |
| tree | 844e9ed8cb0d436dac0c3a6346c74bcd4512a81b /mm/vmstat.c | |
| parent | mm: fix the inaccurate memory statistics issue for users (diff) | |
| download | kernel-db6cc3f4ac2e6cdc898fc9cbc8b32ae1bf56bdad.tar.gz kernel-db6cc3f4ac2e6cdc898fc9cbc8b32ae1bf56bdad.zip | |
Revert "sched/numa: add statistics of numa balance task"
This reverts commit ad6b26b6a0a79166b53209df2ca1cf8636296382.
This commit introduces per-memcg/task NUMA balance statistics, but
unfortunately it introduced a NULL pointer exception due to the following
race condition: After a swap task candidate was chosen, its mm_struct
pointer was set to NULL due to task exit. Later, when performing the
actual task swapping, the p->mm caused the problem.
CPU0 CPU1
:
...
task_numa_migrate
task_numa_find_cpu
task_numa_compare
# a normal task p is chosen
env->best_task = p
# p exit:
exit_signals(p);
p->flags |= PF_EXITING
exit_mm
p->mm = NULL;
migrate_swap_stop
__migrate_swap_task((arg->src_task, arg->dst_cpu)
count_memcg_event_mm(p->mm, NUMA_TASK_SWAP)# p->mm is NULL
task_lock() should be held and the PF_EXITING flag needs to be checked to
prevent this from happening. After discussion, the conclusion was that
adding a lock is not worthwhile for some statistics calculations. Revert
the change and rely on the tracepoint for this purpose.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: ad6b26b6a0a7 ("sched/numa: add statistics of numa balance task")
Signed-off-by: Chen Yu <[email protected]>
Reported-by: Jirka Hladky <[email protected]>
Closes: https://lore.kernel.org/all/CAE4VaGBLJxpd=NeRJXpSCuw=REhC5LWJpC29kDy-Zh2ZDyzQZA@mail.gmail.com/
Reported-by: Srikanth Aithal <[email protected]>
Reported-by: Suneeth D <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Hladky <[email protected]>
Cc: Libo Chen <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Diffstat (limited to 'mm/vmstat.c')
| -rw-r--r-- | mm/vmstat.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c index 429ae5339bfe..a78d70ddeacd 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1346,8 +1346,6 @@ const char * const vmstat_text[] = { "numa_hint_faults", "numa_hint_faults_local", "numa_pages_migrated", - "numa_task_migrated", - "numa_task_swapped", #endif #ifdef CONFIG_MIGRATION "pgmigrate_success", |