commit 5d90ba12b936cea4a0e8028ebe69703e589a3b59
Author: Arkadiusz Miśkiewicz <[email protected]>
Date: Sat Jan 26 13:02:58 2019 +0100
- rel 2; fix pids.current counting
kernel-small_fixes.patch | 110 +++++++++++++++++++++++++++++++++++++++++++++++
kernel.spec | 2 +-
2 files changed, 111 insertions(+), 1 deletion(-)
---
diff --git a/kernel.spec b/kernel.spec
index 8f4a2257..551409d6 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -68,7 +68,7 @@
%define have_pcmcia 0
%endif
-%define rel 1
+%define rel 2
%define basever 4.19
%define postver .16
diff --git a/kernel-small_fixes.patch b/kernel-small_fixes.patch
index 63bd4794..19610274 100644
--- a/kernel-small_fixes.patch
+++ b/kernel-small_fixes.patch
@@ -162,3 +162,113 @@ index 76c92e31afc0..abb5d382f64d 100644
--
cgit 1.2-0.3.lf.el7
+From 48744b6339cf649a69b55997e138c17df1ecc897 Mon Sep 17 00:00:00 2001
+From: Tetsuo Handa <[email protected]>
+Date: Sat, 26 Jan 2019 20:00:51 +0900
+Subject: [PATCH] oom, oom_reaper: do not enqueue same task twice
+
+Arkadiusz reported that enabling memcg's group oom killing causes
+strange memcg statistics where there is no task in a memcg despite
+the number of tasks in that memcg is not 0. It turned out that there
+is a bug in wake_oom_reaper() which allows enqueuing same task twice
+which makes impossible to decrease the number of tasks in that memcg
+due to a refcount leak.
+
+This bug existed since the OOM reaper became invokable from
+task_will_free_mem(current) path in out_of_memory() in Linux 4.7,
+but memcg's group oom killing made it easier to trigger this bug by
+calling wake_oom_reaper() on the same task from one out_of_memory()
+request.
+
+Fix this bug using an approach used by commit 855b018325737f76
+("oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task").
+Since task_will_free_mem(p) == false if p->mm == NULL, we can assume that
+p->mm != NULL when wake_oom_reaper() is called from task_will_free_mem()
+paths. As a side effect of this patch, this patch also avoids enqueuing
+multiple threads sharing memory via task_will_free_mem(current) path.
+
+Signed-off-by: Tetsuo Handa <[email protected]>
+Reported-by: Arkadiusz Miśkiewicz <[email protected]>
+Fixes: af8e15cc85a25315 ("oom, oom_reaper: do not enqueue task if it is on the
oom_reaper_list head")
+---
+ mm/oom_kill.c | 28 +++++++++++++---------------
+ 1 file changed, 13 insertions(+), 15 deletions(-)
+
+diff --git a/mm/oom_kill.c b/mm/oom_kill.c
+index f0e8cd9..457f240 100644
+--- a/mm/oom_kill.c
++++ b/mm/oom_kill.c
+@@ -505,14 +505,6 @@ bool __oom_reap_task_mm(struct mm_struct *mm)
+ struct vm_area_struct *vma;
+ bool ret = true;
+
+- /*
+- * Tell all users of get_user/copy_from_user etc... that the content
+- * is no longer stable. No barriers really needed because unmapping
+- * should imply barriers already and the reader would hit a page fault
+- * if it stumbled over a reaped memory.
+- */
+- set_bit(MMF_UNSTABLE, &mm->flags);
+-
+ for (vma = mm->mmap ; vma; vma = vma->vm_next) {
+ if (!can_madv_dontneed_vma(vma))
+ continue;
+@@ -645,10 +637,15 @@ static int oom_reaper(void *unused)
+ return 0;
+ }
+
+-static void wake_oom_reaper(struct task_struct *tsk)
++static void wake_oom_reaper(struct task_struct *tsk, struct mm_struct *mm)
+ {
+- /* tsk is already queued? */
+- if (tsk == oom_reaper_list || tsk->oom_reaper_list)
++ /*
++ * Tell all users of get_user/copy_from_user etc... that the content
++ * is no longer stable. No barriers really needed because unmapping
++ * should imply barriers already and the reader would hit a page fault
++ * if it stumbled over a reaped memory.
++ */
++ if (test_and_set_bit(MMF_UNSTABLE, &mm->flags))
+ return;
+
+ get_task_struct(tsk);
+@@ -668,7 +665,8 @@ static int __init oom_init(void)
+ }
+ subsys_initcall(oom_init)
+ #else
+-static inline void wake_oom_reaper(struct task_struct *tsk)
++static inline void wake_oom_reaper(struct task_struct *tsk,
++ struct mm_struct *mm)
+ {
+ }
+ #endif /* CONFIG_MMU */
+@@ -915,7 +913,7 @@ static void __oom_kill_process(struct task_struct *victim)
+ rcu_read_unlock();
+
+ if (can_oom_reap)
+- wake_oom_reaper(victim);
++ wake_oom_reaper(victim, mm);
+
+ mmdrop(mm);
+ put_task_struct(victim);
+@@ -955,7 +953,7 @@ static void oom_kill_process(struct oom_control *oc, const
char *message)
+ task_lock(p);
+ if (task_will_free_mem(p)) {
+ mark_oom_victim(p);
+- wake_oom_reaper(p);
++ wake_oom_reaper(p, p->mm);
+ task_unlock(p);
+ put_task_struct(p);
+ return;
+@@ -1085,7 +1083,7 @@ bool out_of_memory(struct oom_control *oc)
+ */
+ if (task_will_free_mem(current)) {
+ mark_oom_victim(current);
+- wake_oom_reaper(current);
++ wake_oom_reaper(current, current->mm);
+ return true;
+ }
+
+--
+1.8.3.1
+
================================================================
---- gitweb:
http://git.pld-linux.org/gitweb.cgi/packages/kernel.git/commitdiff/5d90ba12b936cea4a0e8028ebe69703e589a3b59
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