The patch titled
Subject: mm/mempolicy: cleanup nodemask intersection check for oom
has been added to the -mm tree. Its filename is
mm-mempolicy-cleanup-nodemask-intersection-check-for-oom.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-mempolicy-cleanup-nodemask-intersection-check-for-oom.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-mempolicy-cleanup-nodemask-intersection-check-for-oom.patch
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------------------------------------------------------
From: Feng Tang <feng.tang@xxxxxxxxx>
Subject: mm/mempolicy: cleanup nodemask intersection check for oom
Patch series "mm/mempolicy: some fix and semantics cleanup", v3.
Current memory policy code has some confusing and ambiguous part about
MPOL_LOCAL policy, as it is handled as a faked MPOL_PREFERRED one, and
there are many places having to distinguish them. Also the nodemask
intersection check needs cleanup to be more explicit for OOM use, and
handle MPOL_INTERLEAVE correctly. This patchset cleans up these and
unifies the parameter sanity check for mbind() and set_mempolicy().
This patch (of 3):
mempolicy_nodemask_intersects() is used in oom case to check if a task may
have memory allocated on some memory nodes.
As it's only used by OOM check, rename it to mempolicy_in_oom_domain() to
reduce confusion.
As only for 'bind' policy, the nodemask is a force requirement for from
where to allocate memory, only do the intesection check for it, and return
true for all other policies.
Link: https://lkml.kernel.org/r/1622469956-82897-1-git-send-email-feng.tang@xxxxxxxxx
Link: https://lkml.kernel.org/r/1622469956-82897-2-git-send-email-feng.tang@xxxxxxxxx
Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Ben Widawsky <ben.widawsky@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mempolicy.h | 2 +-
mm/mempolicy.c | 34 +++++++++-------------------------
mm/oom_kill.c | 2 +-
3 files changed, 11 insertions(+), 27 deletions(-)
--- a/include/linux/mempolicy.h~mm-mempolicy-cleanup-nodemask-intersection-check-for-oom
+++ a/include/linux/mempolicy.h
@@ -150,7 +150,7 @@ extern int huge_node(struct vm_area_stru
unsigned long addr, gfp_t gfp_flags,
struct mempolicy **mpol, nodemask_t **nodemask);
extern bool init_nodemask_of_mempolicy(nodemask_t *mask);
-extern bool mempolicy_nodemask_intersects(struct task_struct *tsk,
+extern bool mempolicy_in_oom_domain(struct task_struct *tsk,
const nodemask_t *mask);
extern nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy);
--- a/mm/mempolicy.c~mm-mempolicy-cleanup-nodemask-intersection-check-for-oom
+++ a/mm/mempolicy.c
@@ -2094,16 +2094,16 @@ bool init_nodemask_of_mempolicy(nodemask
#endif
/*
- * mempolicy_nodemask_intersects
+ * mempolicy_in_oom_domain
*
- * 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'
- * policy, always return true since it may allocate elsewhere on fallback.
+ * If tsk's mempolicy is "bind", check for intersection between mask and
+ * the policy nodemask. Otherwise, return true for all other policies
+ * including "interleave", as a tsk with "interleave" policy may have
+ * memory allocated from all nodes in system.
*
* Takes task_lock(tsk) to prevent freeing of its mempolicy.
*/
-bool mempolicy_nodemask_intersects(struct task_struct *tsk,
+bool mempolicy_in_oom_domain(struct task_struct *tsk,
const nodemask_t *mask)
{
struct mempolicy *mempolicy;
@@ -2111,29 +2111,13 @@ bool mempolicy_nodemask_intersects(struc
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;
}
--- a/mm/oom_kill.c~mm-mempolicy-cleanup-nodemask-intersection-check-for-oom
+++ a/mm/oom_kill.c
@@ -104,7 +104,7 @@ static bool oom_cpuset_eligible(struct t
* mempolicy intersects current, otherwise it may be
* needlessly killed.
*/
- ret = mempolicy_nodemask_intersects(tsk, mask);
+ ret = mempolicy_in_oom_domain(tsk, mask);
} else {
/*
* This is not a mempolicy constrained oom, so only
_
Patches currently in -mm which might be from feng.tang@xxxxxxxxx are
mm-mempolicy-cleanup-nodemask-intersection-check-for-oom.patch
mm-mempolicy-dont-handle-mpol_local-like-a-fake-mpol_preferred-policy.patch
mm-mempolicy-unify-the-parameter-sanity-check-for-mbind-and-set_mempolicy.patch
