From 78b132e9bae922f1e8bd9d137f0c27b81c44f15d Mon Sep 17 00:00:00 2001
From: Wei Yang <richard.weiyang@linux.alibaba.com>
Date: Tue, 13 Oct 2020 16:57:08 -0700
Subject: [PATCH] mm/mempolicy: remove or narrow the lock on current
It is not necessary to hold the lock of current when setting nodemask of
a new policy.
Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200921040416.86185-1-richard.weiyang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/mempolicy.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index eddbe4e56c73..69ce708c3a3a 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -875,13 +875,12 @@ 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)
@@ -1324,9 +1323,7 @@ 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
--
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