kernel/git/stable/linux.git/mm, branch linux-2.6.33.y

vm: fix vm_pgoff wrap in upward expansion

2011-11-07T21:47:39+00:00

commit 42c36f63ac1366ab0ecc2d5717821362c259f517 upstream. Commit a626ca6a6564 ("vm: fix vm_pgoff wrap in stack expansion") fixed the case of an expanding mapping causing vm_pgoff wrapping when you had downward stack expansion. But there was another case where IA64 and PA-RISC expand mappings: upward expansion. This fixes that case too. Signed-off-by: Hugh Dickins Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

vm: fix vm_pgoff wrap in stack expansion

2011-11-07T21:47:39+00:00

commit a626ca6a656450e9f4df91d0dda238fff23285f4 upstream. Commit 982134ba6261 ("mm: avoid wrapping vm_pgoff in mremap()") fixed the case of a expanding mapping causing vm_pgoff wrapping when you used mremap. But there was another case where we expand mappings hiding in plain sight: the automatic stack expansion. This fixes that case too. This one also found by Robert Święcki, using his nasty system call fuzzer tool. Good job. Reported-and-tested-by: Robert Święcki Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: fix wrong vmap address calculations with odd NR_CPUS values

2011-08-29T21:32:56+00:00

commit f982f91516fa4cfd9d20518833cd04ad714585be upstream. Commit db64fe02258f ("mm: rewrite vmap layer") introduced code that does address calculations under the assumption that VMAP_BLOCK_SIZE is a power of two. However, this might not be true if CONFIG_NR_CPUS is not set to a power of two. Wrong vmap_block index/offset values could lead to memory corruption. However, this has never been observed in practice (or never been diagnosed correctly); what caught this was the BUG_ON in vb_alloc() that checks for inconsistent vmap_block indices. To fix this, ensure that VMAP_BLOCK_SIZE always is a power of two. BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=31572 Reported-by: Pavel Kysilka Reported-by: Matias A. Fonzo Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter Cc: Nick Piggin Cc: Jeremy Fitzhardinge Cc: Krzysztof Helt Cc: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: prevent concurrent unmap_mapping_range() on the same inode

2011-07-13T03:31:27+00:00

commit 2aa15890f3c191326678f1bd68af61ec6b8753ec upstream. Michael Leun reported that running parallel opens on a fuse filesystem can trigger a "kernel BUG at mm/truncate.c:475" Gurudas Pai reported the same bug on NFS. The reason is, unmap_mapping_range() is not prepared for more than one concurrent invocation per inode. For example: thread1: going through a big range, stops in the middle of a vma and stores the restart address in vm_truncate_count. thread2: comes in with a small (e.g. single page) unmap request on the same vma, somewhere before restart_address, finds that the vma was already unmapped up to the restart address and happily returns without doing anything. Another scenario would be two big unmap requests, both having to restart the unmapping and each one setting vm_truncate_count to its own value. This could go on forever without any of them being able to finish. Truncate and hole punching already serialize with i_mutex. Other callers of unmap_mapping_range() do not, and it's difficult to get i_mutex protection for all callers. In particular ->d_revalidate(), which calls invalidate_inode_pages2_range() in fuse, may be called with or without i_mutex. This patch adds a new mutex to 'struct address_space' to prevent running multiple concurrent unmap_mapping_range() on the same mapping. [ We'll hopefully get rid of all this with the upcoming mm preemptibility series by Peter Zijlstra, the "mm: Remove i_mmap_mutex lockbreak" patch in particular. But that is for 2.6.39 ] Signed-off-by: Miklos Szeredi Reported-by: Michael Leun Reported-by: Gurudas Pai Tested-by: Gurudas Pai Acked-by: Hugh Dickins Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: fix negative commitlimit when gigantic hugepages are allocated

2011-07-13T03:31:24+00:00

commit b0320c7b7d1ac1bd5c2d9dff3258524ab39bad32 upstream. When 1GB hugepages are allocated on a system, free(1) reports less available memory than what really is installed in the box. Also, if the total size of hugepages allocated on a system is over half of the total memory size, CommitLimit becomes a negative number. The problem is that gigantic hugepages (order > MAX_ORDER) can only be allocated at boot with bootmem, thus its frames are not accounted to 'totalram_pages'. However, they are accounted to hugetlb_total_pages() What happens to turn CommitLimit into a negative number is this calculation, in fs/proc/meminfo.c: allowed = ((totalram_pages - hugetlb_total_pages()) * sysctl_overcommit_ratio / 100) + total_swap_pages; A similar calculation occurs in __vm_enough_memory() in mm/mmap.c. Also, every vm statistic which depends on 'totalram_pages' will render confusing values, as if system were 'missing' some part of its memory. Impact of this bug: When gigantic hugepages are allocated and sysctl_overcommit_memory == OVERCOMMIT_NEVER. In a such situation, __vm_enough_memory() goes through the mentioned 'allowed' calculation and might end up mistakenly returning -ENOMEM, thus forcing the system to start reclaiming pages earlier than it would be ususal, and this could cause detrimental impact to overall system's performance, depending on the workload. Besides the aforementioned scenario, I can only think of this causing annoyances with memory reports from /proc/meminfo and free(1). [akpm@linux-foundation.org: standardize comment layout] Reported-by: Russ Anderson Signed-off-by: Rafael Aquini Acked-by: Russ Anderson Cc: Andrea Arcangeli Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

migrate: don't account swapcache as shmem

2011-07-13T03:31:23+00:00

commit 99a15e21d96f6857dafab1e5167e5e8183215c9c upstream. swapcache will reach the below code path in migrate_page_move_mapping, and swapcache is accounted as NR_FILE_PAGES but it's not accounted as NR_SHMEM. Hugh pointed out we must use PageSwapCache instead of comparing mapping to &swapper_space, to avoid build failure with CONFIG_SWAP=n. Signed-off-by: Andrea Arcangeli Acked-by: Hugh Dickins Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ksm: fix NULL pointer dereference in scan_get_next_rmap_item()

2011-07-13T03:31:23+00:00

commit 2b472611a32a72f4a118c069c2d62a1a3f087afd upstream. Andrea Righi reported a case where an exiting task can race against ksmd::scan_get_next_rmap_item (http://lkml.org/lkml/2011/6/1/742) easily triggering a NULL pointer dereference in ksmd. ksm_scan.mm_slot == &ksm_mm_head with only one registered mm CPU 1 (__ksm_exit) CPU 2 (scan_get_next_rmap_item) list_empty() is false lock slot == &ksm_mm_head list_del(slot->mm_list) (list now empty) unlock lock slot = list_entry(slot->mm_list.next) (list is empty, so slot is still ksm_mm_head) unlock slot->mm == NULL ... Oops Close this race by revalidating that the new slot is not simply the list head again. Andrea's test case: #include #include #include #include #define BUFSIZE getpagesize() int main(int argc, char **argv) { void *ptr; if (posix_memalign(&ptr, getpagesize(), BUFSIZE) < 0) { perror("posix_memalign"); exit(1); } if (madvise(ptr, BUFSIZE, MADV_MERGEABLE) < 0) { perror("madvise"); exit(1); } *(char *)NULL = 0; return 0; } Reported-by: Andrea Righi Tested-by: Andrea Righi Cc: Andrea Arcangeli Signed-off-by: Hugh Dickins Signed-off-by: Chris Wright Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: fix ENOSPC returned by handle_mm_fault()

2011-06-23T22:28:39+00:00

commit e0dcd8a05be438b3d2e49ef61441ea3a463663f8 upstream. Al Viro observes that in the hugetlb case, handle_mm_fault() may return a value of the kind ENOSPC when its caller is expecting a value of the kind VM_FAULT_SIGBUS: fix alloc_huge_page()'s failure returns. Signed-off-by: Hugh Dickins Acked-by: Al Viro Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/page_alloc.c: prevent unending loop in __alloc_pages_slowpath()

2011-06-23T22:28:36+00:00

commit cfa54a0fcfc1017c6f122b6f21aaba36daa07f71 upstream. I believe I found a problem in __alloc_pages_slowpath, which allows a process to get stuck endlessly looping, even when lots of memory is available. Running an I/O and memory intensive stress-test I see a 0-order page allocation with __GFP_IO and __GFP_WAIT, running on a system with very little free memory. Right about the same time that the stress-test gets killed by the OOM-killer, the utility trying to allocate memory gets stuck in __alloc_pages_slowpath even though most of the systems memory was freed by the oom-kill of the stress-test. The utility ends up looping from the rebalance label down through the wait_iff_congested continiously. Because order=0, __alloc_pages_direct_compact skips the call to get_page_from_freelist. Because all of the reclaimable memory on the system has already been reclaimed, __alloc_pages_direct_reclaim skips the call to get_page_from_freelist. Since there is no __GFP_FS flag, the block with __alloc_pages_may_oom is skipped. The loop hits the wait_iff_congested, then jumps back to rebalance without ever trying to get_page_from_freelist. This loop repeats infinitely. The test case is pretty pathological. Running a mix of I/O stress-tests that do a lot of fork() and consume all of the system memory, I can pretty reliably hit this on 600 nodes, in about 12 hours. 32GB/node. Signed-off-by: Andrew Barry Signed-off-by: Minchan Kim Reviewed-by: Rik van Riel Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

kmemleak: Do not return a pointer to an object that kmemleak did not get

2011-06-23T22:28:33+00:00

commit 52c3ce4ec5601ee383a14f1485f6bac7b278896e upstream. The kmemleak_seq_next() function tries to get an object (and increment its use count) before returning it. If it could not get the last object during list traversal (because it may have been freed), the function should return NULL rather than a pointer to such object that it did not get. Signed-off-by: Catalin Marinas Reported-by: Phil Carmody Acked-by: Phil Carmody Signed-off-by: Greg Kroah-Hartman