- 14 Jan, 2011 40 commits
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Hugh Dickins authored
2.6.37 added an unmap_and_move_huge_page() for memory failure recovery, but its anon_vma handling was still based around the 2.6.35 conventions. Update it to use page_lock_anon_vma, get_anon_vma, page_unlock_anon_vma, drop_anon_vma in the same way as we're now changing unmap_and_move(). I don't particularly like to propose this for stable when I've not seen its problems in practice nor tested the solution: but it's clearly out of synch at present. Signed-off-by:
Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: <stable@kernel.org> [2.6.37, 2.6.36] Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Hugh Dickins authored
Increased usage of page migration in mmotm reveals that the anon_vma locking in unmap_and_move() has been deficient since 2.6.36 (or even earlier). Review at the time of f1819427 ("mm: fix hang on anon_vma->root->lock") missed the issue here: the anon_vma to which we get a reference may already have been freed back to its slab (it is in use when we check page_mapped, but that can change), and so its anon_vma->root may be switched at any moment by reuse in anon_vma_prepare. Perhaps we could fix that with a get_anon_vma_unless_zero(), but let's not: just rely on page_lock_anon_vma() to do all the hard thinking for us, then we don't need any rcu read locking over here. In removing the rcu_unlock label: since PageAnon is a bit in page->mapping, it's impossible for a !page->mapping page to be anon; but insert VM_BUG_ON in case the implementation ever changes. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:
Mel Gorman <mel@csn.ul.ie> Reviewed-by:
Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: <stable@kernel.org> [2.6.37, 2.6.36] Signed-off-by:
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Hugh Dickins authored
It was hard to explain the page counts which were causing new LTP tests of KSM to fail: we need to drain the per-cpu pagevecs to LRU occasionally. Signed-off-by:
CAI Qian <caiqian@redhat.com> Cc:Andrea Arcangeli <aarcange@redhat.com> Signed-off-by:
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Eric B Munson authored
When parsing changes to the huge page pool sizes made from userspace via the sysfs interface, bogus input values are being covered up by nr_hugepages_store_common and nr_overcommit_hugepages_store returning 0 when strict_strtoul returns an error. This can cause an infinite loop in the nr_hugepages_store code. This patch changes the return value for these functions to -EINVAL when strict_strtoul returns an error. Signed-off-by:
Eric B Munson <emunson@mgebm.net> Reported-by:
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Eric B Munson authored
Huge pages with order >= MAX_ORDER must be allocated at boot via the kernel command line, they cannot be allocated or freed once the kernel is up and running. Currently we allow values to be written to the sysfs and sysctl files controling pool size for these huge page sizes. This patch makes the store functions for nr_hugepages and nr_overcommit_hugepages return -EINVAL when the pool for a page size >= MAX_ORDER is changed. [akpm@linux-foundation.org: avoid multiple return paths in nr_hugepages_store_common()] [caiqian@redhat.com: add checking in hugetlb_overcommit_handler()] Signed-off-by:
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Michal Hocko authored
proc_doulongvec_minmax may fail if the given buffer doesn't represent a valid number. If we provide something invalid we will initialize the resulting value (nr_overcommit_huge_pages in this case) to a random value from the stack. The issue was introduced by a3d0c6aa when the default handler has been replaced by the helper function where we do not check the return value. Reproducer: echo "" > /proc/sys/vm/nr_overcommit_hugepages [akpm@linux-foundation.org: correctly propagate proc_doulongvec_minmax return code] Signed-off-by:
Michal Hocko <mhocko@suse.cz> Cc: CAI Qian <caiqian@redhat.com> Cc: Nishanth Aravamudan <nacc@us.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by:
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Stefan Hajnoczi authored
The sync_inodes_sb() function does not have a return value. Remove the outdated documentation comment. Signed-off-by:
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by:
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Andrew Morton authored
As it stands this code will degenerate into a busy-wait if the calling task has signal_pending(). Cc: Rolf Eike Beer <eike-kernel@sf-tec.de> Signed-off-by:
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Rolf Eike Beer authored
dma_pool_free() scans for the page to free in the pool list holding the pool lock. Then it releases the lock basically to acquire it immediately again. Modify the code to only take the lock once. This will do some additional loops and computations with the lock held in if memory debugging is activated. If it is not activated the only new operations with this lock is one if and one substraction. Signed-off-by:
Rolf Eike Beer <eike-kernel@sf-tec.de> Signed-off-by:
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KyongHo Cho authored
The previous approach of calucation of combined index was page_idx & ~(1 << order)) but we have same result with page_idx & buddy_idx This reduces instructions slightly as well as enhances readability. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix used-unintialised warning] Signed-off-by:
KyongHo Cho <pullip.cho@samsung.com> Signed-off-by:
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Jiri Kosina authored
Even if CONFIG_COMPAT_BRK is set in the kernel configuration, it can still be overriden by randomize_va_space sysctl. If this is the case, the min_brk computation in sys_brk() implementation is wrong, as it solely takes into account COMPAT_BRK setting, assuming that brk start is not randomized. But that might not be the case if randomize_va_space sysctl has been set to '2' at the time the binary has been loaded from disk. In such case, the check has to be done in a same way as in !CONFIG_COMPAT_BRK case. In addition to that, the check for the COMPAT_BRK case introduced back in a5b4592c ("brk: make sys_brk() honor COMPAT_BRK when computing lower bound") is slightly wrong -- the lower bound shouldn't be mm->end_code, but mm->end_data instead, as that's where the legacy applications expect brk section to start (i.e. immediately after last global variable). [akpm@linux-foundation.org: fix comment] Signed-off-by:
Jiri Kosina <jkosina@suse.cz> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by:
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Jesper Juhl authored
The NODEMASK_ALLOC macro may dynamically allocate memory for its second argument ('nodes_allowed' in this context). In nr_hugepages_store_common() we may abort early if strict_strtoul() fails, but in that case we do not free the memory already allocated to 'nodes_allowed', causing a memory leak. This patch closes the leak by freeing the memory in the error path. [akpm@linux-foundation.org: use NODEMASK_FREE, per Minchan Kim] Signed-off-by:Jesper Juhl <jj@chaosbits.net> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by:
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Mel Gorman authored
mm: migration: use rcu_dereference_protected when dereferencing the radix tree slot during file page migration migrate_pages() -> unmap_and_move() only calls rcu_read_lock() for anonymous pages, as introduced by git commit 989f89c5 ("fix rcu_read_lock() in page migraton"). The point of the RCU protection there is part of getting a stable reference to anon_vma and is only held for anon pages as file pages are locked which is sufficient protection against freeing. However, while a file page's mapping is being migrated, the radix tree is double checked to ensure it is the expected page. This uses radix_tree_deref_slot() -> rcu_dereference() without the RCU lock held triggering the following warning. [ 173.674290] =================================================== [ 173.676016] [ INFO: suspicious rcu_dereference_check() usage. ] [ 173.676016] --------------------------------------------------- [ 173.676016] include/linux/radix-tree.h:145 invoked rcu_dereference_check() without protection! [ 173.676016] [ 173.676016] other info that might help us debug this: [ 173.676016] [ 173.676016] [ 173.676016] rcu_scheduler_active = 1, debug_locks = 0 [ 173.676016] 1 lock held by hugeadm/2899: [ 173.676016] #0: (&(&inode->i_data.tree_lock)->rlock){..-.-.}, at: [<c10e3d2b>] migrate_page_move_mapping+0x40/0x1ab [ 173.676016] [ 173.676016] stack backtrace: [ 173.676016] Pid: 2899, comm: hugeadm Not tainted 2.6.37-rc5-autobuild [ 173.676016] Call Trace: [ 173.676016] [<c128cc01>] ? printk+0x14/0x1b [ 173.676016] [<c1063502>] lockdep_rcu_dereference+0x7d/0x86 [ 173.676016] [<c10e3db5>] migrate_page_move_mapping+0xca/0x1ab [ 173.676016] [<c10e41ad>] migrate_page+0x23/0x39 [ 173.676016] [<c10e491b>] buffer_migrate_page+0x22/0x107 [ 173.676016] [<c10e48f9>] ? buffer_migrate_page+0x0/0x107 [ 173.676016] [<c10e425d>] move_to_new_page+0x9a/0x1ae [ 173.676016] [<c10e47e6>] migrate_pages+0x1e7/0x2fa This patch introduces radix_tree_deref_slot_protected() which calls rcu_dereference_protected(). Users of it must pass in the mapping->tree_lock that is protecting this dereference. Holding the tree lock protects against parallel updaters of the radix tree meaning that rcu_dereference_protected is allowable. [akpm@linux-foundation.org: remove unneeded casts] Signed-off-by:
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Andrea Arcangeli authored
Cleanup some code with common compound_trans_head helper. Signed-off-by:
Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Avi Kivity <avi@redhat.com> Signed-off-by:
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Andrea Arcangeli authored
This makes KSM full operational with THP pages. Subpages are scanned while the hugepage is still in place and delivering max cpu performance, and only if there's a match and we're going to deduplicate memory, the single hugepages with the subpage match is split. There will be no false sharing between ksmd and khugepaged. khugepaged won't collapse 2m virtual regions with KSM pages inside. ksmd also should only split pages when the checksum matches and we're likely to split an hugepage for some long living ksm page (usual ksm heuristic to avoid sharing pages that get de-cowed). Signed-off-by:
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Andrea Arcangeli authored
MADV_HUGEPAGE and MADV_NOHUGEPAGE were fully effective only if run after mmap and before touching the memory. While this is enough for most usages, it's little effort to make madvise more dynamic at runtime on an existing mapping by making khugepaged aware about madvise. MADV_HUGEPAGE: register in khugepaged immediately without waiting a page fault (that may not ever happen if all pages are already mapped and the "enabled" knob was set to madvise during the initial page faults). MADV_NOHUGEPAGE: skip vmas marked VM_NOHUGEPAGE in khugepaged to stop collapsing pages where not needed. [akpm@linux-foundation.org: tweak comment] Signed-off-by:
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Andrea Arcangeli authored
Add madvise MADV_NOHUGEPAGE to mark regions that are not important to be hugepage backed. Return -EINVAL if the vma is not of an anonymous type, or the feature isn't built into the kernel. Never silently return success. Signed-off-by:
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Andrea Arcangeli authored
Define MADV_NOHUGEPAGE. Signed-off-by:
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Andrea Arcangeli authored
Read compound_trans_order safe. Noop for CONFIG_TRANSPARENT_HUGEPAGE=n. Signed-off-by:
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Andrea Arcangeli authored
hugetlbfs was changed to allow memory failure to migrate the hugetlbfs pages and that broke THP as split_huge_page was then called on hugetlbfs pages too. compound_head/order was also run unsafe on THP pages that can be splitted at any time. All compound_head() invocations in memory-failure.c that are run on pages that aren't pinned and that can be freed and reused from under us (while compound_head is running) are buggy because compound_head can return a dangling pointer, but I'm not fixing this as this is a generic memory-failure bug not specific to THP but it applies to hugetlbfs too, so I can fix it later after THP is merged upstream. Signed-off-by:
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Andrea Arcangeli authored
Add debug checks for invariants that if broken could lead to mapcount vs page_mapcount debug checks to trigger later in split_huge_page. Signed-off-by:
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David Rientjes authored
Add hugepage statistics to per-node sysfs meminfo Reviewed-by:
David Rientjes <rientjes@google.com> Signed-off-by:
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Rik van Riel authored
Make sure we scale up nr_rotated when we encounter a referenced transparent huge page. This ensures pageout scanning balance is not distorted when there are huge pages on the LRU. Signed-off-by:
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Rik van Riel authored
Count each transparent hugepage as HPAGE_PMD_NR pages in the LRU statistics, so the Active(anon) and Inactive(anon) statistics in /proc/meminfo are correct. Signed-off-by:
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Rik van Riel authored
On small systems, the extra memory used by the anti-fragmentation memory reserve and simply because huge pages are smaller than large pages can easily outweigh the benefits of less TLB misses. A less obvious concern is if run on a NUMA machine with asymmetric node sizes and one of them is very small. The reserve could make the node unusable. In case of the crashdump kernel, OOMs have been observed due to the anti-fragmentation memory reserve taking up a large fraction of the crashdump image. This patch disables transparent hugepages on systems with less than 1GB of RAM, but the hugepage subsystem is fully initialized so administrators can enable THP through /sys if desired. Signed-off-by:
Avi Kiviti <avi@redhat.com> Signed-off-by:
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Andrea Arcangeli authored
It makes no sense not to enable compaction for small order pages as we don't want to end up with bad order 2 allocations and good and graceful order 9 allocations. Signed-off-by:
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Andrea Arcangeli authored
This takes advantage of memory compaction to properly generate pages of order > 0 if regular page reclaim fails and priority level becomes more severe and we don't reach the proper watermarks. Signed-off-by:
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Andrea Arcangeli authored
It's unclear why schedule friendly kernel threads can't be taken away by the CPU through the scheduler itself. It's safer to stop them as they can trigger memory allocation, if kswapd also freezes itself to avoid generating I/O they have too. Signed-off-by:
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Andrea Arcangeli authored
For GRU and EPT, we need gup-fast to set referenced bit too (this is why it's correct to return 0 when shadow_access_mask is zero, it requires gup-fast to set the referenced bit). qemu-kvm access already sets the young bit in the pte if it isn't zero-copy, if it's zero copy or a shadow paging EPT minor fault we relay on gup-fast to signal the page is in use... We also need to check the young bits on the secondary pagetables for NPT and not nested shadow mmu as the data may never get accessed again by the primary pte. Without this closer accuracy, we'd have to remove the heuristic that avoids collapsing hugepages in hugepage virtual regions that have not even a single subpage in use. ->test_young is full backwards compatible with GRU and other usages that don't have young bits in pagetables set by the hardware and that should nuke the secondary mmu mappings when ->clear_flush_young runs just like EPT does. Removing the heuristic that checks the young bit in khugepaged/collapse_huge_page completely isn't so bad either probably but I thought it was worth it and this makes it reliable. Signed-off-by:
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Andrea Arcangeli authored
Archs implementing Transparent Hugepage Support must implement a function called has_transparent_hugepage to be sure the virtual or physical CPU supports Transparent Hugepages. Signed-off-by:
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Andrea Arcangeli authored
An huge pmd can only be mapped if the corresponding 2M virtual range is fully contained in the vma. At times the VM calls split_vma twice, if the first split_vma succeeds and the second fail, the first split_vma remains in effect and it's not rolled back. For split_vma or vma_adjust to fail an allocation failure is needed so it's a very unlikely event (the out of memory killer would normally fire before any allocation failure is visible to kernel and userland and if an out of memory condition happens it's unlikely to happen exactly here). Nevertheless it's safer to ensure that no huge pmd can be left around if the vma is adjusted in a way that can't fit hugepages anymore at the new vm_start/vm_end address. Signed-off-by:
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Andrea Arcangeli authored
It's not worth migrating transparent hugepages during compaction. Those hugepages don't create fragmentation. Signed-off-by:
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Andrea Arcangeli authored
With transparent hugepage support we need compaction for the "defrag" sysfs controls to be effective. At the moment THP hangs the system if COMPACTION isn't selected, as without COMPACTION lumpy reclaim wouldn't be entirely disabled. So at the moment it's not orthogonal. When lumpy will be removed from the VM I can remove the select COMPACTION in theory, but then 99% of THP users would be still doing a mistake in disabling compaction, even if the mistake won't return in fatal runtime but just slightly degraded performance. So from a theoretical standpoing forcing the below select is not needed (the dependency isn't strict nor at compile time nor at runtime) but from a practical standpoint it is safer. If anybody really wants THP to run without compaction, it'd be such a weird setup that editing the Kconfig file to allow it will be surely not a problem. Signed-off-by:
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Andrea Arcangeli authored
Allow to choose between the always|madvise default for page faults and khugepaged at config time. madvise guarantees zero risk of higher memory footprint for applications (applications using madvise(MADV_HUGEPAGE) won't risk to use any more memory by backing their virtual regions with hugepages). Initially set the default to N and don't depend on EMBEDDED. Signed-off-by:
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Andrea Arcangeli authored
This tries to be more friendly to filesystem in userland, with userland backends that allocate memory in the I/O paths and that could deadlock if khugepaged holds the mmap_sem write mode of the userland backend while allocating memory. Memory allocation may wait for writeback I/O completion from the daemon that may be blocked in the mmap_sem read mode if a page fault happens and the daemon wasn't using mlock for the memory required for the I/O submission and completion. Signed-off-by:
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Andrea Arcangeli authored
It's mostly a matter of replacing alloc_pages with alloc_pages_vma after introducing alloc_pages_vma. khugepaged needs special handling as the allocation has to happen inside collapse_huge_page where the vma is known and an error has to be returned to the outer loop to sleep alloc_sleep_millisecs in case of failure. But it retains the more efficient logic of handling allocation failures in khugepaged in case of CONFIG_NUMA=n. Signed-off-by:
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Andrea Arcangeli authored
With memory compaction in, and lumpy-reclaim disabled, it seems safe enough to defrag memory during the (synchronous) transparent hugepage page faults (TRANSPARENT_HUGEPAGE_DEFRAG_FLAG) and not only during khugepaged (async) hugepage allocations that was already enabled even before memory compaction was in (TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG). Signed-off-by:
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Andrea Arcangeli authored
If transparent hugepage is enabled initialize min_free_kbytes to an optimal value by default. This moves the hugeadm algorithm in kernel. Signed-off-by:
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Johannes Weiner authored
Natively handle huge pmds when changing page tables on behalf of mprotect(). I left out update_mmu_cache() because we do not need it on x86 anyway but more importantly the interface works on ptes, not pmds. Signed-off-by:
Johannes Weiner <hannes@cmpxchg.org> Signed-off-by:
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Johannes Weiner authored
Flushing the tlb for huge pmds requires the vma's anon_vma, so pass along the vma instead of the mm, we can always get the latter when we need it. Signed-off-by:
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