Skip to contentSkip to conversation

mm-oom_kill-allow-process_mrelease-to-run-under-mmap_lock-protection.patch removed from -mm tree

merged [email protected] 1 participant 1 message Jan 20, 2022

lore
Share & tools
lore

[email protected]

author tree notice Applied
#0 lore raw

The patch titled
Subject: mm/oom_kill: allow process_mrelease to run under mmap_lock protection
has been removed from the -mm tree. Its filename was
mm-oom_kill-allow-process_mrelease-to-run-under-mmap_lock-protection.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Suren Baghdasaryan <[email protected]>
Subject: mm/oom_kill: allow process_mrelease to run under mmap_lock protection

With exit_mmap holding mmap_write_lock during free_pgtables call, process_mrelease does not need to elevate mm->mm_users in order to prevent exit_mmap from destrying pagetables while __oom_reap_task_mm is walking the VMA tree. The change prevents process_mrelease from calling the last mmput, which can lead to waiting for IO completion in exit_aio.

Link https://lkml.kernel.org/r/[email protected] open here
Signed-off-by Suren Baghdasaryan <[email protected]>
Acked-by Michal Hocko <[email protected]>
Reviewed-by Jason Gunthorpe <[email protected]>
Cc Andrea Arcangeli <[email protected]>
Cc Andy Lutomirski <[email protected]>
Cc Christian Brauner <[email protected]>
Cc Christian Brauner <[email protected]>
Cc Christoph Hellwig <[email protected]>
Cc David Hildenbrand <[email protected]>
Cc David Rientjes <[email protected]>
Cc Florian Weimer <[email protected]>
Cc Jan Engelhardt <[email protected]>
Cc Jann Horn <[email protected]>
Cc Johannes Weiner <[email protected]>
Cc Kirill A. Shutemov <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc Minchan Kim <[email protected]>
Cc Oleg Nesterov <[email protected]>
Cc Rik van Riel <[email protected]>
Cc Roman Gushchin <[email protected]>
Cc Shakeel Butt <[email protected]>
Cc Tim Murray <[email protected]>
Signed-off-by Andrew Morton <[email protected]>

---

 mm/oom_kill.c |   27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)
mm/oom_kill.c renamed from mm/oom_kill.c~mm-oom_kill-allow-process_mrelease-to-run-under-mmap_lock-protection +15 -12
@@ -1170,15 +1170,15 @@ SYSCALL_DEFINE2(process_mrelease, int, p
 		goto put_task;
 	}
 
-	if (mmget_not_zero(p->mm)) {
-		mm = p->mm;
-		if (task_will_free_mem(p))
-			reap = true;
-		else {
-			/* Error only if the work has not been done already */
-			if (!test_bit(MMF_OOM_SKIP, &mm->flags))
-				ret = -EINVAL;
-		}
+	mm = p->mm;
+	mmgrab(mm);
+
+	if (task_will_free_mem(p))
+		reap = true;
+	else {
+		/* Error only if the work has not been done already */
+		if (!test_bit(MMF_OOM_SKIP, &mm->flags))
+			ret = -EINVAL;
 	}
 	task_unlock(p);
 

@@ -1189,13 +1189,16 @@ SYSCALL_DEFINE2(process_mrelease, int, p
 		ret = -EINTR;
 		goto drop_mm;
 	}
-	if (!__oom_reap_task_mm(mm))
+	/*
+	 * Check MMF_OOM_SKIP again under mmap_read_lock protection to ensure
+	 * possible change in exit_mmap is seen
+	 */
+	if (!test_bit(MMF_OOM_SKIP, &mm->flags) && !__oom_reap_task_mm(mm))
 		ret = -EAGAIN;
 	mmap_read_unlock(mm);
 
 drop_mm:
-	if (mm)
-		mmput(mm);
+	mmdrop(mm);
 put_task:
 	put_task_struct(task);
 	return ret;

_

Patches currently in -mm which might be from [email protected] are