The patch titled
oom: hold tasklist_lock when dumping tasks
has been added to the -mm tree. Its filename is
oom-hold-tasklist_lock-when-dumping-tasks.patch
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------------------------------------------------------
Subject: oom: hold tasklist_lock when dumping tasks
From: David Rientjes <rientjes@xxxxxxxxxx>
dump_header() always requires tasklist_lock to be held because it calls
dump_tasks() which iterates through the tasklist. There are a few places
where this isn't maintained, so make sure tasklist_lock is always held
whenever calling dump_header().
This also fixes the pagefault case where oom_kill_process() is called on
current without tasklist_lock. It is necessary to hold a readlock for
both calling dump_header() and iterating its children.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Reported-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
diff -puN mm/oom_kill.c~oom-hold-tasklist_lock-when-dumping-tasks mm/oom_kill.c
--- a/mm/oom_kill.c~oom-hold-tasklist_lock-when-dumping-tasks
+++ a/mm/oom_kill.c
@@ -400,6 +400,9 @@ static void dump_tasks(const struct mem_
} while_each_thread(g, p);
}
+/*
+ * Call with tasklist_lock read-locked.
+ */
static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
struct mem_cgroup *mem)
{
@@ -646,8 +649,8 @@ retry:
/* Found nothing?!?! Either we hang forever, or we panic. */
if (!p) {
- read_unlock(&tasklist_lock);
dump_header(NULL, gfp_mask, order, NULL);
+ read_unlock(&tasklist_lock);
panic("Out of memory and no killable processes...\n");
}
@@ -680,11 +683,6 @@ void out_of_memory(struct zonelist *zone
/* Got some memory back in the last second. */
return;
- if (sysctl_panic_on_oom == 2) {
- dump_header(NULL, gfp_mask, order, NULL);
- panic("out of memory. Compulsory panic_on_oom is selected.\n");
- }
-
/*
* Check if there were limitations on the allocation (only relevant for
* NUMA) that may require different handling.
@@ -693,15 +691,12 @@ void out_of_memory(struct zonelist *zone
&totalpages);
read_lock(&tasklist_lock);
if (unlikely(sysctl_panic_on_oom)) {
- /*
- * panic_on_oom only affects CONSTRAINT_NONE, the kernel
- * should not panic for cpuset or mempolicy induced memory
- * failures.
- */
- if (constraint == CONSTRAINT_NONE) {
+ if (sysctl_panic_on_oom == 2 || constraint == CONSTRAINT_NONE) {
dump_header(NULL, gfp_mask, order, NULL);
read_unlock(&tasklist_lock);
- panic("Out of memory: panic_on_oom is enabled\n");
+ panic("Out of memory: %s panic_on_oom is enabled\n",
+ sysctl_panic_on_oom == 2 ? "compulsory" :
+ "system-wide");
}
}
__out_of_memory(gfp_mask, order, totalpages, constraint, nodemask);
@@ -729,8 +724,10 @@ void pagefault_out_of_memory(void)
if (try_set_system_oom()) {
constrained_alloc(NULL, 0, NULL, &totalpages);
+ read_lock(&tasklist_lock);
err = oom_kill_process(current, 0, 0, 0, totalpages, NULL,
"Out of memory (pagefault)");
+ read_unlock(&tasklist_lock);
if (err)
out_of_memory(NULL, 0, 0, NULL);
clear_system_oom();
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
linux-next.patch
acpi-map-pxms-to-low-node-ids.patch
mempolicy-remove-redundant-code.patch
oom-filter-tasks-not-sharing-the-same-cpuset.patch
oom-sacrifice-child-with-highest-badness-score-for-parent.patch
oom-select-task-from-tasklist-for-mempolicy-ooms.patch
oom-remove-special-handling-for-pagefault-ooms.patch
oom-badness-heuristic-rewrite.patch
oom-deprecate-oom_adj-tunable.patch
oom-replace-sysctls-with-quick-mode.patch
oom-avoid-oom-killer-for-lowmem-allocations.patch
oom-remove-unnecessary-code-and-cleanup.patch
oom-default-to-killing-current-for-pagefault-ooms.patch
oom-avoid-race-for-oom-killed-tasks-detaching-mm-prior-to-exit.patch
oom-select_bad_process-check-pf_kthread-instead-of-mm-to-skip-kthreads.patch
oom-select_bad_process-pf_exiting-check-should-take-mm-into-account.patch
oom-introduce-find_lock_task_mm-to-fix-mm-false-positives.patch
oom-oom_forkbomb_penalty-move-thread_group_cputime-out-of-task_lock.patch
oom-hold-tasklist_lock-when-dumping-tasks.patch
oom-give-current-access-to-memory-reserves-if-it-has-been-killed.patch
oom-avoid-sending-exiting-tasks-a-sigkill.patch
oom-clean-up-oom_kill_task.patch
oom-clean-up-oom_badness.patch
mempolicy-remove-case-mpol_interleave-from-policy_zonelist.patch
mempolicy-remove-redundant-check.patch
mempolicy-dont-call-mpol_set_nodemask-when-no_context.patch
mempolicy-lose-unnecessary-loop-variable-in-mpol_parse_str.patch
mempolicy-rename-policy_types-and-cleanup-initialization.patch
mempolicy-factor-mpol_shared_policy_init-return-paths.patch
mempolicy-document-cpuset-interaction-with-tmpfs-mpol-mount-option.patch
mm-default-to-node-zonelist-ordering-when-nodes-have-only-lowmem.patch
oom-move-sysctl-declarations-to-oomh.patch
memcg-oom-wakeup-filter.patch
memcg-oom-wakeup-filter-update.patch
memcg-oom-notifier.patch
memcg-oom-notifier-update.patch
memcg-oom-kill-disable-and-oom-status.patch
memcg-oom-kill-disable-and-oom-status-update.patch
--
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