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authorJoonsoo Kim <js1304@gmail.com>2015-02-27 15:51:43 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-28 09:57:50 -0800
commitda616534ed7f6e8ffaab699258b55c8d78d0b4ea (patch)
tree764a6f1ab8eb3898bcf4125425e90a35a6a9d5b0
parent01945fa248ff6d34f5fdb8106118910b77b76f91 (diff)
mm/nommu: fix memory leak
Maxime reported the following memory leak regression due to commit dbc8358c7237 ("mm/nommu: use alloc_pages_exact() rather than its own implementation"). On v3.19, I am facing a memory leak. Each time I run a command one page is lost. Here an example with busybox's free command: / # free total used free shared buffers cached Mem: 7928 1972 5956 0 0 492 -/+ buffers/cache: 1480 6448 / # free total used free shared buffers cached Mem: 7928 1976 5952 0 0 492 -/+ buffers/cache: 1484 6444 / # free total used free shared buffers cached Mem: 7928 1980 5948 0 0 492 -/+ buffers/cache: 1488 6440 / # free total used free shared buffers cached Mem: 7928 1984 5944 0 0 492 -/+ buffers/cache: 1492 6436 / # free total used free shared buffers cached Mem: 7928 1988 5940 0 0 492 -/+ buffers/cache: 1496 6432 At some point, the system fails to sastisfy 256KB allocations: free: page allocation failure: order:6, mode:0xd0 CPU: 0 PID: 67 Comm: free Not tainted 3.19.0-05389-gacf2cf1-dirty #64 Hardware name: STM32 (Device Tree Support) show_stack+0xb/0xc warn_alloc_failed+0x97/0xbc __alloc_pages_nodemask+0x295/0x35c __get_free_pages+0xb/0x24 alloc_pages_exact+0x19/0x24 do_mmap_pgoff+0x423/0x658 vm_mmap_pgoff+0x3f/0x4e load_flat_file+0x20d/0x4f8 load_flat_binary+0x3f/0x26c search_binary_handler+0x51/0xe4 do_execveat_common+0x271/0x35c do_execve+0x19/0x1c ret_fast_syscall+0x1/0x4a Mem-info: Normal per-cpu: CPU 0: hi: 0, btch: 1 usd: 0 active_anon:0 inactive_anon:0 isolated_anon:0 active_file:0 inactive_file:0 isolated_file:0 unevictable:123 dirty:0 writeback:0 unstable:0 free:1515 slab_reclaimable:17 slab_unreclaimable:139 mapped:0 shmem:0 pagetables:0 bounce:0 free_cma:0 Normal free:6060kB min:352kB low:440kB high:528kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:492kB isolated(anon):0ks lowmem_reserve[]: 0 0 Normal: 23*4kB (U) 22*8kB (U) 24*16kB (U) 23*32kB (U) 23*64kB (U) 23*128kB (U) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 6060kB 123 total pagecache pages 2048 pages of RAM 1538 free pages 66 reserved pages 109 slab pages -46 pages shared 0 pages swap cached nommu: Allocation of length 221184 from process 67 (free) failed Normal per-cpu: CPU 0: hi: 0, btch: 1 usd: 0 active_anon:0 inactive_anon:0 isolated_anon:0 active_file:0 inactive_file:0 isolated_file:0 unevictable:123 dirty:0 writeback:0 unstable:0 free:1515 slab_reclaimable:17 slab_unreclaimable:139 mapped:0 shmem:0 pagetables:0 bounce:0 free_cma:0 Normal free:6060kB min:352kB low:440kB high:528kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:492kB isolated(anon):0ks lowmem_reserve[]: 0 0 Normal: 23*4kB (U) 22*8kB (U) 24*16kB (U) 23*32kB (U) 23*64kB (U) 23*128kB (U) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 6060kB 123 total pagecache pages Unable to allocate RAM for process text/data, errno 12 SEGV This problem happens because we allocate ordered page through __get_free_pages() in do_mmap_private() in some cases and we try to free individual pages rather than ordered page in free_page_series(). In this case, freeing pages whose refcount is not 0 won't be freed to the page allocator so memory leak happens. To fix the problem, this patch changes __get_free_pages() to alloc_pages_exact() since alloc_pages_exact() returns physically-contiguous pages but each pages are refcounted. Fixes: dbc8358c7237 ("mm/nommu: use alloc_pages_exact() rather than its own implementation"). Reported-by: Maxime Coquelin <mcoquelin.stm32@gmail.com> Tested-by: Maxime Coquelin <mcoquelin.stm32@gmail.com> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: <stable@vger.kernel.org> [3.19] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/nommu.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/mm/nommu.c b/mm/nommu.c
index 7296360fc057..3e67e7538ecf 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1213,11 +1213,9 @@ static int do_mmap_private(struct vm_area_struct *vma,
if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
total = point;
kdebug("try to alloc exact %lu pages", total);
- base = alloc_pages_exact(len, GFP_KERNEL);
- } else {
- base = (void *)__get_free_pages(GFP_KERNEL, order);
}
+ base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL);
if (!base)
goto enomem;