The patch titled
Subject: oom: split out forced OOM killer
has been added to the -mm tree. Its filename is
oom-split-out-forced-oom-killer.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/oom-split-out-forced-oom-killer.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/oom-split-out-forced-oom-killer.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxx>
Subject: oom: split out forced OOM killer
The forced OOM killing is currently wired into out_of_memory() call even
though their objective is different which makes the code ugly and harder
to follow. Generic out_of_memory path has to deal with configuration
settings and heuristics which are completely irrelevant to the forced OOM
killer (e.g. sysctl_oom_kill_allocating_task or OOM killer prevention for
already dying tasks). All of them are either relying on explicit
force_kill check or indirectly by checking current->mm which is always
NULL for sysrq+f. This is not nice, hard to follow and error prone.
Let's pull forced OOM killer code out into a separate function
(force_out_of_memory) which is really trivial now. As a bonus we can
clearly state that this is a forced OOM killer in the OOM message which is
helpful to distinguish it from the regular OOM killer.
Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Jakob Unterwurzacher <jakobunt@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/tty/sysrq.c | 9 ------
include/linux/oom.h | 1
mm/oom_kill.c | 57 ++++++++++++++++++++++++++++--------------
3 files changed, 41 insertions(+), 26 deletions(-)
diff -puN drivers/tty/sysrq.c~oom-split-out-forced-oom-killer drivers/tty/sysrq.c
--- a/drivers/tty/sysrq.c~oom-split-out-forced-oom-killer
+++ a/drivers/tty/sysrq.c
@@ -353,15 +353,8 @@ static struct sysrq_key_op sysrq_term_op
static void moom_callback(struct work_struct *ignored)
{
- const gfp_t gfp_mask = GFP_KERNEL;
- struct oom_context oc = {
- .zonelist = node_zonelist(first_memory_node, gfp_mask),
- .gfp_mask = gfp_mask,
- .force_kill = true,
- };
-
mutex_lock(&oom_lock);
- if (!out_of_memory(&oc))
+ if (!force_out_of_memory())
pr_info("OOM request ignored because killer is disabled\n");
mutex_unlock(&oom_lock);
}
diff -puN include/linux/oom.h~oom-split-out-forced-oom-killer include/linux/oom.h
--- a/include/linux/oom.h~oom-split-out-forced-oom-killer
+++ a/include/linux/oom.h
@@ -77,6 +77,7 @@ extern enum oom_scan_t oom_scan_process_
struct task_struct *task, unsigned long totalpages);
extern bool out_of_memory(struct oom_context *oc);
+extern bool force_out_of_memory(void);
extern void exit_oom_victim(void);
diff -puN mm/oom_kill.c~oom-split-out-forced-oom-killer mm/oom_kill.c
--- a/mm/oom_kill.c~oom-split-out-forced-oom-killer
+++ a/mm/oom_kill.c
@@ -627,6 +627,38 @@ int unregister_oom_notifier(struct notif
EXPORT_SYMBOL_GPL(unregister_oom_notifier);
/**
+ * force_out_of_memory - forces OOM killer to kill a process
+ *
+ * Explicitly trigger the OOM killer. The system doesn't have to be under
+ * OOM condition (e.g. sysrq+f).
+ */
+bool force_out_of_memory(void)
+{
+ struct task_struct *p;
+ unsigned long totalpages;
+ unsigned int points;
+ const gfp_t gfp_mask = GFP_KERNEL;
+ struct oom_context oc = {
+ .zonelist = node_zonelist(first_memory_node, gfp_mask),
+ .gfp_mask = gfp_mask,
+ .force_kill = true,
+ };
+
+ if (oom_killer_disabled)
+ return false;
+
+ constrained_alloc(&oc, &totalpages);
+ p = select_bad_process(&oc, &points, totalpages);
+ if (p != (void *)-1UL)
+ oom_kill_process(&oc, p, points, totalpages, NULL,
+ "Forced out of memory killer");
+ else
+ pr_warn("Sysrq triggered out of memory. No killable task found...\n");
+
+ return true;
+}
+
+/**
* out_of_memory - kill the "best" process when we run out of memory
* @oc: pointer to struct oom_context
*
@@ -647,12 +679,10 @@ bool out_of_memory(struct oom_context *o
if (oom_killer_disabled)
return false;
- if (!oc->force_kill) {
- blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
- if (freed > 0)
- /* Got some memory back in the last second. */
- goto out;
- }
+ blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
+ if (freed > 0)
+ /* Got some memory back in the last second. */
+ goto out;
/*
* If current has a pending SIGKILL or is exiting, then automatically
@@ -675,13 +705,8 @@ bool out_of_memory(struct oom_context *o
constraint = constrained_alloc(oc, &totalpages);
if (constraint != CONSTRAINT_MEMORY_POLICY)
oc->nodemask = NULL;
- if (!oc->force_kill)
- check_panic_on_oom(oc, constraint, NULL);
+ check_panic_on_oom(oc, constraint, NULL);
- /*
- * not affecting force_kill because sysrq triggered OOM killer runs from
- * the workqueue context so current->mm will be NULL
- */
if (sysctl_oom_kill_allocating_task && current->mm &&
!oom_unkillable_task(current, NULL, oc->nodemask) &&
current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
@@ -694,12 +719,8 @@ bool out_of_memory(struct oom_context *o
p = select_bad_process(oc, &points, totalpages);
/* Found nothing?!?! Either we hang forever, or we panic. */
if (!p) {
- if (!oc->force_kill) {
- dump_header(oc, NULL, NULL);
- panic("Out of memory and no killable processes...\n");
- } else {
- pr_info("Sysrq triggered out of memory. No killable task found...\n");
- }
+ dump_header(oc, NULL, NULL);
+ panic("Out of memory and no killable processes...\n");
}
if (p != (void *)-1UL) {
oom_kill_process(oc, p, points, totalpages, NULL,
_
Patches currently in -mm which might be from mhocko@xxxxxxx are
origin.patch
mm-mlock-refactor-mlock-munlock-and-munlockall-code.patch
mm-mlock-add-new-mlock-munlock-and-munlockall-system-calls.patch
mm-mlock-introduce-vm_lockonfault-and-add-mlock-flags-to-enable-it.patch
mm-mmap-add-mmap-flag-to-request-vm_lockonfault.patch
selftests-vm-add-tests-for-lock-on-fault.patch
oom-do-not-panic-when-oom-killer-is-sysrq-triggered.patch
oom-do-not-invoke-oom-notifiers-on-sysrqf.patch
mm-oom-organize-oom-context-into-struct.patch
oom-split-out-forced-oom-killer.patch
page-flags-trivial-cleanup-for-pagetrans-helpers.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages.patch
page-flags-define-pg_locked-behavior-on-compound-pages.patch
page-flags-define-behavior-of-fs-io-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-lru-related-flags-on-compound-pages.patch
page-flags-define-behavior-slb-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-xen-related-flags-on-compound-pages.patch
page-flags-define-pg_reserved-behavior-on-compound-pages.patch
page-flags-define-pg_swapbacked-behavior-on-compound-pages.patch
page-flags-define-pg_swapcache-behavior-on-compound-pages.patch
page-flags-define-pg_mlocked-behavior-on-compound-pages.patch
page-flags-define-pg_uncached-behavior-on-compound-pages.patch
page-flags-define-pg_uptodate-behavior-on-compound-pages.patch
page-flags-look-on-head-page-if-the-flag-is-encoded-in-page-mapping.patch
mm-sanitize-page-mapping-for-tail-pages.patch
mm-vmscan-fix-the-page-state-calculation-in-too_many_isolated.patch
mm-page_isolation-check-pfn-validity-before-access.patch
mm-support-madvisemadv_free.patch
mm-support-madvisemadv_free-fix-2.patch
mm-dont-split-thp-page-when-syscall-is-called.patch
mm-dont-split-thp-page-when-syscall-is-called-fix-2.patch
mm-dont-split-thp-page-when-syscall-is-called-fix-3.patch
mm-move-lazy-free-pages-to-inactive-list.patch
mm-move-lazy-free-pages-to-inactive-list-fix.patch
mm-move-lazy-free-pages-to-inactive-list-fix-fix.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
