This is a note to let you know that I've just added the patch titled
mm: fix mlock accouting
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-fix-mlock-accouting.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7162a1e87b3e380133dadc7909081bb70d0a7041 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Date: Thu, 21 Jan 2016 16:40:27 -0800
Subject: mm: fix mlock accouting
From: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
commit 7162a1e87b3e380133dadc7909081bb70d0a7041 upstream.
Tetsuo Handa reported underflow of NR_MLOCK on munlock.
Testcase:
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#define BASE ((void *)0x400000000000)
#define SIZE (1UL << 21)
int main(int argc, char *argv[])
{
void *addr;
system("grep Mlocked /proc/meminfo");
addr = mmap(BASE, SIZE, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED | MAP_FIXED,
-1, 0);
if (addr == MAP_FAILED)
printf("mmap() failed\n"), exit(1);
munmap(addr, SIZE);
system("grep Mlocked /proc/meminfo");
return 0;
}
It happens on munlock_vma_page() due to unfortunate choice of nr_pages
data type:
__mod_zone_page_state(zone, NR_MLOCK, -nr_pages);
For unsigned int nr_pages, implicitly casted to long in
__mod_zone_page_state(), it becomes something around UINT_MAX.
munlock_vma_page() usually called for THP as small pages go though
pagevec.
Let's make nr_pages signed int.
Similar fixes in 6cdb18ad98a4 ("mm/vmstat: fix overflow in
mod_zone_page_state()") used `long' type, but `int' here is OK for a
count of the number of sub-pages in a huge page.
Fixes: ff6a6da60b89 ("mm: accelerate munlock() treatment of THP pages")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Tested-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/mlock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -172,7 +172,7 @@ static void __munlock_isolation_failed(s
*/
unsigned int munlock_vma_page(struct page *page)
{
- unsigned int nr_pages;
+ int nr_pages;
struct zone *zone = page_zone(page);
/* For try_to_munlock() and to serialize with page migration */
Patches currently in stable-queue which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
queue-3.14/drivers-scsi-sg.c-mark-vma-as-vm_io-to-prevent-migration.patch
queue-3.14/mm-fix-mlock-accouting.patch
queue-3.14/scsi-add-marvell-console-to-vpd-blacklist.patch
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