diff options
| author | Dennis Zhou <dennis@kernel.org> | 2024-10-07 17:19:42 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-11-06 20:11:11 -0800 |
| commit | 018d24539d9ed7531245a381ba24f5d9e8714682 (patch) | |
| tree | 97e5b9de1f08d65dfedcfbb2aa1451f06e5ee838 | |
| parent | bd40b053fabe27209cb240d205a0c817cbe5fb87 (diff) | |
percpu: fix data race with pcpu_nr_empty_pop_pages
Fixes the data race by moving the read to be behind the pcpu_lock. This
is okay because the code (initially) above it will not increase the
empty populated page count because it is populating backing pages that
already have allocations served out of them.
Link: https://lkml.kernel.org/r/20241008001942.8114-1-dennis@kernel.org
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202407191651.f24e499d-oliver.sang@intel.com
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/percpu.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/mm/percpu.c b/mm/percpu.c index da21680ff294..d1a73cf65c53 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1864,6 +1864,10 @@ restart: area_found: pcpu_stats_area_alloc(chunk, size); + + if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW) + pcpu_schedule_balance_work(); + spin_unlock_irqrestore(&pcpu_lock, flags); /* populate if not all pages are already there */ @@ -1891,9 +1895,6 @@ area_found: mutex_unlock(&pcpu_alloc_mutex); } - if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW) - pcpu_schedule_balance_work(); - /* clear the areas and return address relative to base address */ for_each_possible_cpu(cpu) memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size); |