[RFC Patch v2 1/4] mm/mempolicy: skip nodemask intersect check for 'interleave' when oom
From: Feng Tang <hidden>
Date: 2021-05-20 08:30:40
Also in:
lkml
Subsystem:
memory management, memory management - memory policy and migration, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
mempolicy_nodemask_intersects() is used in oom case to check if a task may have memory allocated on some memory nodes. MPOL_INTERLEAVE has set a nodemask, which is not a forced requirement, but just a hint for chosing a node to allocate memory from, and the task may have memory allocated on other nodes than this nodemask. So skip the check. Suggested-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Feng Tang <redacted> --- mm/mempolicy.c | 24 ++++-------------------- 1 file changed, 4 insertions(+), 20 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d79fa29..1964cca 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c@@ -2098,7 +2098,7 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask) * * If tsk's mempolicy is "default" [NULL], return 'true' to indicate default * policy. Otherwise, check for intersection between mask and the policy - * nodemask for 'bind' or 'interleave' policy. For 'preferred' or 'local' + * nodemask for 'bind' policy. For 'interleave', 'preferred' or 'local' * policy, always return true since it may allocate elsewhere on fallback. * * Takes task_lock(tsk) to prevent freeing of its mempolicy.
@@ -2111,29 +2111,13 @@ bool mempolicy_nodemask_intersects(struct task_struct *tsk, if (!mask) return ret; + task_lock(tsk); mempolicy = tsk->mempolicy; - if (!mempolicy) - goto out; - - switch (mempolicy->mode) { - case MPOL_PREFERRED: - /* - * MPOL_PREFERRED and MPOL_F_LOCAL are only preferred nodes to - * allocate from, they may fallback to other nodes when oom. - * Thus, it's possible for tsk to have allocated memory from - * nodes in mask. - */ - break; - case MPOL_BIND: - case MPOL_INTERLEAVE: + if (mempolicy && mempolicy->mode == MPOL_BIND) ret = nodes_intersects(mempolicy->v.nodes, *mask); - break; - default: - BUG(); - } -out: task_unlock(tsk); + return ret; }
--
2.7.4