kernel/linux.git/mm, branch v3.0.95

vm: add no-mmu vm_iomap_memory() stub

2013-08-20T15:21:01+00:00

commit 3c0b9de6d37a481673e81001c57ca0e410c72346 upstream. I think we could just move the full vm_iomap_memory() function into util.h or similar, but I didn't get any reply from anybody actually using nommu even to this trivial patch, so I'm not going to touch it any more than required. Here's the fairly minimal stub to make the nommu case at least potentially work. It doesn't seem like anybody cares, though. Signed-off-by: Linus Torvalds Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

futex: Take hugepages into account when generating futex_key

2013-08-20T15:21:01+00:00

commit 13d60f4b6ab5b702dc8d2ee20999f98a93728aec upstream. The futex_keys of process shared futexes are generated from the page offset, the mapping host and the mapping index of the futex user space address. This should result in an unique identifier for each futex. Though this is not true when futexes are located in different subpages of an hugepage. The reason is, that the mapping index for all those futexes evaluates to the index of the base page of the hugetlbfs mapping. So a futex at offset 0 of the hugepage mapping and another one at offset PAGE_SIZE of the same hugepage mapping have identical futex_keys. This happens because the futex code blindly uses page->index. Steps to reproduce the bug: 1. Map a file from hugetlbfs. Initialize pthread_mutex1 at offset 0 and pthread_mutex2 at offset PAGE_SIZE of the hugetlbfs mapping. The mutexes must be initialized as PTHREAD_PROCESS_SHARED because PTHREAD_PROCESS_PRIVATE mutexes are not affected by this issue as their keys solely depend on the user space address. 2. Lock mutex1 and mutex2 3. Create thread1 and in the thread function lock mutex1, which results in thread1 blocking on the locked mutex1. 4. Create thread2 and in the thread function lock mutex2, which results in thread2 blocking on the locked mutex2. 5. Unlock mutex2. Despite the fact that mutex2 got unlocked, thread2 still blocks on mutex2 because the futex_key points to mutex1. To solve this issue we need to take the normal page index of the page which contains the futex into account, if the futex is in an hugetlbfs mapping. In other words, we calculate the normal page mapping index of the subpage in the hugetlbfs mapping. Mappings which are not based on hugetlbfs are not affected and still use page->index. Thanks to Mel Gorman who provided a patch for adding proper evaluation functions to the hugetlbfs code to avoid exposing hugetlbfs specific details to the futex code. [ tglx: Massaged changelog ] Signed-off-by: Zhang Yi Reviewed-by: Jiang Biao Tested-by: Ma Chenggong Reviewed-by: 'Mel Gorman' Acked-by: 'Darren Hart' Cc: 'Peter Zijlstra' Link: http://lkml.kernel.org/r/000101ce71a6%24a83c5880%24f8b50980%24@com Signed-off-by: Thomas Gleixner Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman

mm/memory-hotplug: fix lowmem count overflow when offline pages

2013-08-04T07:43:42+00:00

commit cea27eb2a202959783f81254c48c250ddd80e129 upstream. The logic for the memory-remove code fails to correctly account the Total High Memory when a memory block which contains High Memory is offlined as shown in the example below. The following patch fixes it. Before logic memory remove: MemTotal: 7603740 kB MemFree: 6329612 kB Buffers: 94352 kB Cached: 872008 kB SwapCached: 0 kB Active: 626932 kB Inactive: 519216 kB Active(anon): 180776 kB Inactive(anon): 222944 kB Active(file): 446156 kB Inactive(file): 296272 kB Unevictable: 0 kB Mlocked: 0 kB HighTotal: 7294672 kB HighFree: 5704696 kB LowTotal: 309068 kB LowFree: 624916 kB After logic memory remove: MemTotal: 7079452 kB MemFree: 5805976 kB Buffers: 94372 kB Cached: 872000 kB SwapCached: 0 kB Active: 626936 kB Inactive: 519236 kB Active(anon): 180780 kB Inactive(anon): 222944 kB Active(file): 446156 kB Inactive(file): 296292 kB Unevictable: 0 kB Mlocked: 0 kB HighTotal: 7294672 kB HighFree: 5181024 kB LowTotal: 4294752076 kB LowFree: 624952 kB [mhocko@suse.cz: fix CONFIG_HIGHMEM=n build] Signed-off-by: Wanpeng Li Reviewed-by: Michal Hocko Cc: KAMEZAWA Hiroyuki Cc: David Rientjes Cc: [2.6.24+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Zhouping Liu Signed-off-by: Greg Kroah-Hartman

mm: migration: add migrate_entry_wait_huge()

2013-06-20T18:28:20+00:00

commit 30dad30922ccc733cfdbfe232090cf674dc374dc upstream. When we have a page fault for the address which is backed by a hugepage under migration, the kernel can't wait correctly and do busy looping on hugepage fault until the migration finishes. As a result, users who try to kick hugepage migration (via soft offlining, for example) occasionally experience long delay or soft lockup. This is because pte_offset_map_lock() can't get a correct migration entry or a correct page table lock for hugepage. This patch introduces migration_entry_wait_huge() to solve this. Signed-off-by: Naoya Horiguchi Reviewed-by: Rik van Riel Reviewed-by: Wanpeng Li Reviewed-by: Michal Hocko Cc: Mel Gorman Cc: Andi Kleen Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

swap: avoid read_swap_cache_async() race to deadlock while waiting on discard I/O completion

2013-06-20T18:28:20+00:00

commit cbab0e4eec299e9059199ebe6daf48730be46d2b upstream. read_swap_cache_async() can race against get_swap_page(), and stumble across a SWAP_HAS_CACHE entry in the swap map whose page wasn't brought into the swapcache yet. This transient swap_map state is expected to be transitory, but the actual placement of discard at scan_swap_map() inserts a wait for I/O completion thus making the thread at read_swap_cache_async() to loop around its -EEXIST case, while the other end at get_swap_page() is scheduled away at scan_swap_map(). This can leave the system deadlocked if the I/O completion happens to be waiting on the CPU waitqueue where read_swap_cache_async() is busy looping and !CONFIG_PREEMPT. This patch introduces a cond_resched() call to make the aforementioned read_swap_cache_async() busy loop condition to bail out when necessary, thus avoiding the subtle race window. Signed-off-by: Rafael Aquini Acked-by: Johannes Weiner Acked-by: KOSAKI Motohiro Acked-by: Hugh Dickins Cc: Shaohua Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/THP: use pmd_populate() to update the pmd with pgtable_t pointer

2013-06-07T19:46:37+00:00

commit 7c3425123ddfdc5f48e7913ff59d908789712b18 upstream. We should not use set_pmd_at to update pmd_t with pgtable_t pointer. set_pmd_at is used to set pmd with huge pte entries and architectures like ppc64, clear few flags from the pte when saving a new entry. Without this change we observe bad pte errors like below on ppc64 with THP enabled. BUG: Bad page map in process ld mm=0xc000001ee39f4780 pte:7fc3f37848000001 pmd:c000001ec0000000 Signed-off-by: Aneesh Kumar K.V Cc: Hugh Dickins Cc: Benjamin Herrenschmidt Reviewed-by: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: mmu_notifier: re-fix freed page still mapped in secondary MMU

2013-06-07T19:46:36+00:00

commit d34883d4e35c0a994e91dd847a82b4c9e0c31d83 upstream. Commit 751efd8610d3 ("mmu_notifier_unregister NULL Pointer deref and multiple ->release()") breaks the fix 3ad3d901bbcf ("mm: mmu_notifier: fix freed page still mapped in secondary MMU"). Since hlist_for_each_entry_rcu() is changed now, we can not revert that patch directly, so this patch reverts the commit and simply fix the bug spotted by that patch This bug spotted by commit 751efd8610d3 is: There is a race condition between mmu_notifier_unregister() and __mmu_notifier_release(). Assume two tasks, one calling mmu_notifier_unregister() as a result of a filp_close() ->flush() callout (task A), and the other calling mmu_notifier_release() from an mmput() (task B). A B t1 srcu_read_lock() t2 if (!hlist_unhashed()) t3 srcu_read_unlock() t4 srcu_read_lock() t5 hlist_del_init_rcu() t6 synchronize_srcu() t7 srcu_read_unlock() t8 hlist_del_rcu() <--- NULL pointer deref. This can be fixed by using hlist_del_init_rcu instead of hlist_del_rcu. The another issue spotted in the commit is "multiple ->release() callouts", we needn't care it too much because it is really rare (e.g, can not happen on kvm since mmu-notify is unregistered after exit_mmap()) and the later call of multiple ->release should be fast since all the pages have already been released by the first call. Anyway, this issue should be fixed in a separate patch. -stable suggestions: Any version that has commit 751efd8610d3 need to be backported. I find the oldest version has this commit is 3.0-stable. [akpm@linux-foundation.org: tweak comments] Signed-off-by: Xiao Guangrong Tested-by: Robin Holt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm compaction: fix of improper cache flush in migration code

2013-06-07T19:46:36+00:00

commit c2cc499c5bcf9040a738f49e8051b42078205748 upstream. Page 'new' during MIGRATION can't be flushed with flush_cache_page(). Using flush_cache_page(vma, addr, pfn) is justified only if the page is already placed in process page table, and that is done right after flush_cache_page(). But without it the arch function has no knowledge of process PTE and does nothing. Besides that, flush_cache_page() flushes an application cache page, but the kernel has a different page virtual address and dirtied it. Replace it with flush_dcache_page(new) which is the proper usage. The old page is flushed in try_to_unmap_one() before migration. This bug takes place in Sead3 board with M14Kc MIPS CPU without cache aliasing (but Harvard arch - separate I and D cache) in tight memory environment (128MB) each 1-3days on SOAK test. It fails in cc1 during kernel build (SIGILL, SIGBUS, SIGSEG) if CONFIG_COMPACTION is switched ON. Signed-off-by: Leonid Yegoshin Cc: Leonid Yegoshin Acked-by: Rik van Riel Cc: Michal Hocko Acked-by: Mel Gorman Cc: Ralf Baechle Cc: Russell King Cc: David Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

vm: add vm_iomap_memory() helper function

2013-04-26T04:23:49+00:00

commit b4cbb197c7e7a68dbad0d491242e3ca67420c13e upstream. Various drivers end up replicating the code to mmap() their memory buffers into user space, and our core memory remapping function may be very flexible but it is unnecessarily complicated for the common cases to use. Our internal VM uses pfn's ("page frame numbers") which simplifies things for the VM, and allows us to pass physical addresses around in a denser and more efficient format than passing a "phys_addr_t" around, and having to shift it up and down by the page size. But it just means that drivers end up doing that shifting instead at the interface level. It also means that drivers end up mucking around with internal VM things like the vma details (vm_pgoff, vm_start/end) way more than they really need to. So this just exports a function to map a certain physical memory range into user space (using a phys_addr_t based interface that is much more natural for a driver) and hides all the complexity from the driver. Some drivers will still end up tweaking the vm_page_prot details for things like prefetching or cacheability etc, but that's actually relevant to the driver, rather than caring about what the page offset of the mapping is into the particular IO memory region. Acked-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds

hugetlbfs: add swap entry check in follow_hugetlb_page()

2013-04-26T04:23:47+00:00

commit 9cc3a5bd40067b9a0fbd49199d0780463fc2140f upstream. With applying the previous patch "hugetlbfs: stop setting VM_DONTDUMP in initializing vma(VM_HUGETLB)" to reenable hugepage coredump, if a memory error happens on a hugepage and the affected processes try to access the error hugepage, we hit VM_BUG_ON(atomic_read(&page->_count) <= 0) in get_page(). The reason for this bug is that coredump-related code doesn't recognise "hugepage hwpoison entry" with which a pmd entry is replaced when a memory error occurs on a hugepage. In other words, physical address information is stored in different bit layout between hugepage hwpoison entry and pmd entry, so follow_hugetlb_page() which is called in get_dump_page() returns a wrong page from a given address. The expected behavior is like this: absent is_swap_pte FOLL_DUMP Expected behavior ------------------------------------------------------------------- true false false hugetlb_fault false true false hugetlb_fault false false false return page true false true skip page (to avoid allocation) false true true hugetlb_fault false false true return page With this patch, we can call hugetlb_fault() and take proper actions (we wait for migration entries, fail with VM_FAULT_HWPOISON_LARGE for hwpoisoned entries,) and as the result we can dump all hugepages except for hwpoisoned ones. Signed-off-by: Naoya Horiguchi Cc: Rik van Riel Acked-by: Michal Hocko Cc: HATAYAMA Daisuke Acked-by: KOSAKI Motohiro Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman