Messages in this thread Patch in this message | | | From | Abel Wu <> | Subject | [PATCH] mm/mempolicy: fix lock contention on mems_allowed | Date | Tue, 9 Aug 2022 18:49:27 +0800 |
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The mems_allowed field can be modified by other tasks, so it isn't safe to access it with alloc_lock unlocked even in the current process context.
Fixes: 78b132e9bae9 ("mm/mempolicy: remove or narrow the lock on current") Signed-off-by: Abel Wu <wuyun.abel@bytedance.com> --- mm/mempolicy.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index d39b01fd52fe..ae422e44affb 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -855,12 +855,14 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags, goto out; } + task_lock(current); ret = mpol_set_nodemask(new, nodes, scratch); if (ret) { + task_unlock(current); mpol_put(new); goto out; } - task_lock(current); + old = current->mempolicy; current->mempolicy = new; if (new && new->mode == MPOL_INTERLEAVE) @@ -1295,7 +1297,9 @@ static long do_mbind(unsigned long start, unsigned long len, NODEMASK_SCRATCH(scratch); if (scratch) { mmap_write_lock(mm); + task_lock(current); err = mpol_set_nodemask(new, nmask, scratch); + task_unlock(current); if (err) mmap_write_unlock(mm); } else -- 2.31.1
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