2020-09-21 04:07:42

by Wei Yang

[permalink] [raw]
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 <[email protected]>
---
mm/mempolicy.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 906adc58d86f..3fde772ef5ef 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
--
2.20.1 (Apple Git-117)