This is a note to let you know that I've just added the patch titled mm: fix mlock accouting to the 4.4-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-4.4 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-4.4/mm-thp-khugepaged-call-pte-flush-at-the-time-of-collapse.patch queue-4.4/ipc-shm-handle-removed-segments-gracefully-in-shm_mmap.patch queue-4.4/drivers-scsi-sg.c-mark-vma-as-vm_io-to-prevent-migration.patch queue-4.4/mm-fix-mlock-accouting.patch queue-4.4/mm-replace-vma_lock_anon_vma-with-anon_vma_lock_read-write.patch queue-4.4/mm-fix-regression-in-remap_file_pages-emulation.patch queue-4.4/scsi-add-marvell-console-to-vpd-blacklist.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html