diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-01-21 16:40:27 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-25 12:01:21 -0800 |
| commit | 918a2c388ed7828fa4b6ccb5cacd9e422f30938c (patch) | |
| tree | b754e9060e91cdd26ee81a383f8235ee2344090e | |
| parent | 6e8ea2f2258caf0d2a876b36c15a93788a7cde93 (diff) | |
mm: fix mlock accouting
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@linux.intel.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Michel Lespinasse <walken@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | mm/mlock.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mlock.c b/mm/mlock.c index 339d9e0949b6..d6006b146fea 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -172,7 +172,7 @@ static void __munlock_isolation_failed(struct page *page) */ 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 */ |