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* mm: use NUMA_NO_NODEDavid Rientjes2013-02-244-23/+26
| | | | | | | | | | Make a sweep through mm/ and convert code that uses -1 directly to using the more appropriate NUMA_NO_NODE. Signed-off-by: David Rientjes <rientjes@google.com> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mmu_notifier_unregister NULL Pointer deref and multiple ->release() calloutsRobin Holt2013-02-241-40/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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. Additionally, the list traversal in __mmu_notifier_release() is not protected by the by the mmu_notifier_mm->hlist_lock which can result in callouts to the ->release() notifier from both mmu_notifier_unregister() and __mmu_notifier_release(). -stable suggestions: The stable trees prior to 3.7.y need commits 21a92735f660 and 70400303ce0c cherry-picked in that order prior to cherry-picking this commit. The 3.7.y tree already has those two commits. Signed-off-by: Robin Holt <holt@sgi.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Avi Kivity <avi@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Sagi Grimberg <sagig@mellanox.co.il> Cc: Haggai Eran <haggaie@mellanox.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/memory_hotplug: use pgdat_end_pfn() instead of open coding the same.Cody P Schafer2013-02-241-1/+1
| | | | | | | | | | | | Replace open coded pgdat_end_pfn() with helper function. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/memory_hotplug: use ensure_zone_is_initialized()Cody P Schafer2013-02-241-19/+10
| | | | | | | | | | | | Remove open coding of ensure_zone_is_initialzied(). Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add helper ensure_zone_is_initialized()Cody P Schafer2013-02-241-0/+11
| | | | | | | | | | | | | | | ensure_zone_is_initialized() checks if a zone is in a empty & not initialized state (typically occuring after it is created in memory hotplugging), and, if so, calls init_currently_empty_zone() to initialize the zone. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/page_alloc: add informative debugging message in ↵Cody P Schafer2013-02-241-0/+7
| | | | | | | | | | | | | | | | | page_outside_zone_boundaries() Add a debug message which prints when a page is found outside of the boundaries of the zone it should belong to. Format is: "page $pfn outside zone [ $start_pfn - $end_pfn ]" [akpm@linux-foundation.org: s/pr_debug/pr_err/] Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mmzone: add pgdat_{end_pfn,is_empty}() helpers & consolidate.Cody P Schafer2013-02-241-4/+10
| | | | | | | | | | | | | | | Add pgdat_end_pfn() and pgdat_is_empty() helpers which match the similar zone_*() functions. Change node_end_pfn() to be a wrapper of pgdat_end_pfn(). Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/page_alloc: add a VM_BUG in __free_one_page() if the zone is uninitialized.Cody P Schafer2013-02-241-0/+2
| | | | | | | | | | | | | | | | Freeing pages to uninitialized zones is not handled by __free_one_page(), and should never happen when the code is correct. Ran into this while writing some code that dynamically onlines extra zones. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add zone_is_empty() and zone_is_initialized()Cody P Schafer2013-02-241-0/+10
| | | | | | | | | | | | | Factoring out these 2 checks makes it more clear what we are actually checking for. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add & use zone_end_pfn() and zone_spans_pfn()Cody P Schafer2013-02-246-27/+32
| | | | | | | | | | | | | | | | | | | | | | Add 2 helpers (zone_end_pfn() and zone_spans_pfn()) to reduce code duplication. This also switches to using them in compaction (where an additional variable needed to be renamed), page_alloc, vmstat, memory_hotplug, and kmemleak. Note that in compaction.c I avoid calling zone_end_pfn() repeatedly because I expect at some point the sycronization issues with start_pfn & spanned_pages will need fixing, either by actually using the seqlock or clever memory barrier usage. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: add SECTION_IN_PAGE_FLAGSCody P Schafer2013-02-241-2/+6
| | | | | | | | | | | | | Instead of directly utilizing a combination of config options to determine this, add a macro to specifically address it. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: David Hansen <dave@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mlock.c: document scary-looking stack expansion mlock chainJohannes Weiner2013-02-241-0/+4
| | | | | | | | | | | | | | | | | | The fact that mlock calls get_user_pages, and get_user_pages might call mlock when expanding a stack looks like a potential recursion. However, mlock makes sure the requested range is already contained within a vma, so no stack expansion will actually happen from mlock. Should this ever change: the stack expansion mlocks only the newly expanded range and so will not result in recursive expansion. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Cc: Hugh Dickins <hughd@google.com> Acked-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: refactor inactive_file_is_low() to use get_lru_size()Johannes Weiner2013-02-243-31/+6
| | | | | | | | | | | | | | | | | | An inactive file list is considered low when its active counterpart is bigger, regardless of whether it is a global zone LRU list or a memcg zone LRU list. The only difference is in how the LRU size is assessed. get_lru_size() does the right thing for both global and memcg reclaim situations. Get rid of inactive_file_is_low_global() and mem_cgroup_inactive_file_is_low() by using get_lru_size() and compare the numbers in common code. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: shmem: use new radix tree iteratorJohannes Weiner2013-02-241-13/+12
| | | | | | | | | | | | In shmem_find_get_pages_and_swap(), use the faster radix tree iterator construct from commit 78c1d78488a3 ("radix-tree: introduce bit-optimized iterator"). Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hugh Dickins <hughd@google.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: stop hotremove lockdep warningHugh Dickins2013-02-241-14/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Complaints are rare, but lockdep still does not understand the way ksm_memory_callback(MEM_GOING_OFFLINE) takes ksm_thread_mutex, and holds it until the ksm_memory_callback(MEM_OFFLINE): that appears to be a problem because notifier callbacks are made under down_read of blocking_notifier_head->rwsem (so first the mutex is taken while holding the rwsem, then later the rwsem is taken while still holding the mutex); but is not in fact a problem because mem_hotplug_mutex is held throughout the dance. There was an attempt to fix this with mutex_lock_nested(); but if that happened to fool lockdep two years ago, apparently it does so no longer. I had hoped to eradicate this issue in extending KSM page migration not to need the ksm_thread_mutex. But then realized that although the page migration itself is safe, we do still need to lock out ksmd and other users of get_ksm_page() while offlining memory - at some point between MEM_GOING_OFFLINE and MEM_OFFLINE, the struct pages themselves may vanish, and get_ksm_page()'s accesses to them become a violation. So, give up on holding ksm_thread_mutex itself from MEM_GOING_OFFLINE to MEM_OFFLINE, and add a KSM_RUN_OFFLINE flag, and wait_while_offlining() checks, to achieve the same lockout without being caught by lockdep. This is less elegant for KSM, but it's more important to keep lockdep useful to other users - and I apologize for how long it took to fix. Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove offlining arg to migrate_pagesHugh Dickins2013-02-247-46/+29
| | | | | | | | | | | | | | | | | No functional change, but the only purpose of the offlining argument to migrate_pages() etc, was to ensure that __unmap_and_move() could migrate a KSM page for memory hotremove (which took ksm_thread_mutex) but not for other callers. Now all cases are safe, remove the arg. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: enable KSM page migrationHugh Dickins2013-02-242-20/+4
| | | | | | | | | | | | | | | | | | | | | | | | | Migration of KSM pages is now safe: remove the PageKsm restrictions from mempolicy.c and migrate.c. But keep PageKsm out of __unmap_and_move()'s anon_vma contortions, which are irrelevant to KSM: it looks as if that code was preventing hotremove migration of KSM pages, unless they happened to be in swapcache. There is some question as to whether enforcing a NUMA mempolicy migration ought to migrate KSM pages, mapped into entirely unrelated processes; but moving page_mapcount > 1 is only permitted with MPOL_MF_MOVE_ALL anyway, and it seems reasonable to assume that you wouldn't set MADV_MERGEABLE on any area where this is a worry. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: make !merge_across_nodes migration safeHugh Dickins2013-02-241-30/+134
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The new KSM NUMA merge_across_nodes knob introduces a problem, when it's set to non-default 0: if a KSM page is migrated to a different NUMA node, how do we migrate its stable node to the right tree? And what if that collides with an existing stable node? ksm_migrate_page() can do no more than it's already doing, updating stable_node->kpfn: the stable tree itself cannot be manipulated without holding ksm_thread_mutex. So accept that a stable tree may temporarily indicate a page belonging to the wrong NUMA node, leave updating until the next pass of ksmd, just be careful not to merge other pages on to a misplaced page. Note nid of holding tree in stable_node, and recognize that it will not always match nid of kpfn. A misplaced KSM page is discovered, either when ksm_do_scan() next comes around to one of its rmap_items (we now have to go to cmp_and_merge_page even on pages in a stable tree), or when stable_tree_search() arrives at a matching node for another page, and this node page is found misplaced. In each case, move the misplaced stable_node to a list of migrate_nodes (and use the address of migrate_nodes as magic by which to identify them): we don't need them in a tree. If stable_tree_search() finds no match for a page, but it's currently exiled to this list, then slot its stable_node right there into the tree, bringing all of its mappings with it; otherwise they get migrated one by one to the original page of the colliding node. stable_tree_search() is now modelled more like stable_tree_insert(), in order to handle these insertions of migrated nodes. remove_node_from_stable_tree(), remove_all_stable_nodes() and ksm_check_stable_tree() have to handle the migrate_nodes list as well as the stable tree itself. Less obviously, we do need to prune the list of stale entries from time to time (scan_get_next_rmap_item() does it once each full scan): whereas stale nodes in the stable tree get naturally pruned as searches try to brush past them, these migrate_nodes may get forgotten and accumulate. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: make KSM page migration possibleHugh Dickins2013-02-242-22/+77
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | KSM page migration is already supported in the case of memory hotremove, which takes the ksm_thread_mutex across all its migrations to keep life simple. But the new KSM NUMA merge_across_nodes knob introduces a problem, when it's set to non-default 0: if a KSM page is migrated to a different NUMA node, how do we migrate its stable node to the right tree? And what if that collides with an existing stable node? So far there's no provision for that, and this patch does not attempt to deal with it either. But how will I test a solution, when I don't know how to hotremove memory? The best answer is to enable KSM page migration in all cases now, and test more common cases. With THP and compaction added since KSM came in, page migration is now mainstream, and it's a shame that a KSM page can frustrate freeing a page block. Without worrying about merge_across_nodes 0 for now, this patch gets KSM page migration working reliably for default merge_across_nodes 1 (but leave the patch enabling it until near the end of the series). It's much simpler than I'd originally imagined, and does not require an additional tier of locking: page migration relies on the page lock, KSM page reclaim relies on the page lock, the page lock is enough for KSM page migration too. Almost all the care has to be in get_ksm_page(): that's the function which worries about when a stable node is stale and should be freed, now it also has to worry about the KSM page being migrated. The only new overhead is an additional put/get/lock/unlock_page when stable_tree_search() arrives at a matching node: to make sure migration respects the raised page count, and so does not migrate the page while we're busy with it here. That's probably avoidable, either by changing internal interfaces from using kpage to stable_node, or by moving the ksm_migrate_page() callsite into a page_freeze_refs() section (even if not swapcache); but this works well, I've no urge to pull it apart now. (Descents of the stable tree may pass through nodes whose KSM pages are under migration: being unlocked, the raised page count does not prevent that, nor need it: it's safe to memcmp against either old or new page.) You might worry about mremap, and whether page migration's rmap_walk to remove migration entries will find all the KSM locations where it inserted earlier: that should already be handled, by the satisfyingly heavy hammer of move_vma()'s call to ksm_madvise(,,,MADV_UNMERGEABLE,). Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: remove old stable nodes more thoroughlyHugh Dickins2013-02-243-28/+92
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Switching merge_across_nodes after running KSM is liable to oops on stale nodes still left over from the previous stable tree. It's not something that people will often want to do, but it would be lame to demand a reboot when they're trying to determine which merge_across_nodes setting is best. How can this happen? We only permit switching merge_across_nodes when pages_shared is 0, and usually set run 2 to force that beforehand, which ought to unmerge everything: yet oopses still occur when you then run 1. Three causes: 1. The old stable tree (built according to the inverse merge_across_nodes) has not been fully torn down. A stable node lingers until get_ksm_page() notices that the page it references no longer references it: but the page is not necessarily freed as soon as expected, particularly when swapcache. Fix this with a pass through the old stable tree, applying get_ksm_page() to each of the remaining nodes (most found stale and removed immediately), with forced removal of any left over. Unless the page is still mapped: I've not seen that case, it shouldn't occur, but better to WARN_ON_ONCE and EBUSY than BUG. 2. __ksm_enter() has a nice little optimization, to insert the new mm just behind ksmd's cursor, so there's a full pass for it to stabilize (or be removed) before ksmd addresses it. Nice when ksmd is running, but not so nice when we're trying to unmerge all mms: we were missing those mms forked and inserted behind the unmerge cursor. Easily fixed by inserting at the end when KSM_RUN_UNMERGE. 3. It is possible for a KSM page to be faulted back from swapcache into an mm, just after unmerge_and_remove_all_rmap_items() scanned past it. Fix this by copying on fault when KSM_RUN_UNMERGE: but that is private to ksm.c, so dissolve the distinction between ksm_might_need_to_copy() and ksm_does_need_to_copy(), doing it all in the one call into ksm.c. A long outstanding, unrelated bugfix sneaks in with that third fix: ksm_does_need_to_copy() would copy from a !PageUptodate page (implying I/O error when read in from swap) to a page which it then marks Uptodate. Fix this case by not copying, letting do_swap_page() discover the error. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: get_ksm_page lockedHugh Dickins2013-02-241-10/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In some places where get_ksm_page() is used, we need the page to be locked. When KSM migration is fully enabled, we shall want that to make sure that the page just acquired cannot be migrated beneath us (raised page count is only effective when there is serialization to make sure migration notices). Whereas when navigating through the stable tree, we certainly do not want to lock each node (raised page count is enough to guarantee the memcmps, even if page is migrated to another node). Since we're about to add another use case, add the locked argument to get_ksm_page() now. Hmm, what's that rcu_read_lock() about? Complete misunderstanding, I really got the wrong end of the stick on that! There's a configuration in which page_cache_get_speculative() can do something cheaper than get_page_unless_zero(), relying on its caller's rcu_read_lock() to have disabled preemption for it. There's no need for rcu_read_lock() around get_page_unless_zero() (and mapping checks) here. Cut out that silliness before making this any harder to understand. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: reorganize ksm_check_stable_treeHugh Dickins2013-02-241-16/+22
| | | | | | | | | | | | | | | | | Memory hotremove's ksm_check_stable_tree() is pitifully inefficient (restarting whenever it finds a stale node to remove), but rearrange so that at least it does not needlessly restart from nid 0 each time. And add a couple of comments: here is why we keep pfn instead of page. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: trivial tidyupsHugh Dickins2013-02-241-26/+22
| | | | | | | | | | | | | | | | | | | | | | | | Add NUMA() and DO_NUMA() macros to minimize blight of #ifdef CONFIG_NUMAs (but indeed we don't want to expand struct rmap_item by nid when not NUMA). Add comment, remove "unsigned" from rmap_item->nid, as "int nid" elsewhere. Define ksm_merge_across_nodes 1U when #ifndef NUMA to help optimizing out. Use ?: in get_kpfn_nid(). Adjust a few comments noticed in ongoing work. Leave stable_tree_insert()'s rb_linkage until after the node has been set up, as unstable_tree_search_insert() does: ksm_thread_mutex and page lock make either way safe, but we're going to copy and I prefer this precedent. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: add sysfs ABI DocumentationPetr Holasek2013-02-241-0/+52
| | | | | | | | | | | | | | | Add sysfs documentation for Kernel Samepage Merging (KSM) including new merge_across_nodes knob. Signed-off-by: Petr Holasek <pholasek@redhat.com> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ksm: allow trees per NUMA nodePetr Holasek2013-02-242-19/+139
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Here's a KSM series, based on mmotm 2013-01-23-17-04: starting with Petr's v7 "KSM: numa awareness sysfs knob"; then fixing the two issues we had with that, fully enabling KSM page migration on the way. (A different kind of KSM/NUMA issue which I've certainly not begun to address here: when KSM pages are unmerged, there's usually no sense in preferring to allocate the new pages local to the caller's node.) This patch: Introduces new sysfs boolean knob /sys/kernel/mm/ksm/merge_across_nodes which control merging pages across different numa nodes. When it is set to zero only pages from the same node are merged, otherwise pages from all nodes can be merged together (default behavior). Typical use-case could be a lot of KVM guests on NUMA machine and cpus from more distant nodes would have significant increase of access latency to the merged ksm page. Sysfs knob was choosen for higher variability when some users still prefers higher amount of saved physical memory regardless of access latency. Every numa node has its own stable & unstable trees because of faster searching and inserting. Changing of merge_across_nodes value is possible only when there are not any ksm shared pages in system. I've tested this patch on numa machines with 2, 4 and 8 nodes and measured speed of memory access inside of KVM guests with memory pinned to one of nodes with this benchmark: http://pholasek.fedorapeople.org/alloc_pg.c Population standard deviations of access times in percentage of average were following: merge_across_nodes=1 2 nodes 1.4% 4 nodes 1.6% 8 nodes 1.7% merge_across_nodes=0 2 nodes 1% 4 nodes 0.32% 8 nodes 0.018% RFC: https://lkml.org/lkml/2011/11/30/91 v1: https://lkml.org/lkml/2012/1/23/46 v2: https://lkml.org/lkml/2012/6/29/105 v3: https://lkml.org/lkml/2012/9/14/550 v4: https://lkml.org/lkml/2012/9/23/137 v5: https://lkml.org/lkml/2012/12/10/540 v6: https://lkml.org/lkml/2012/12/23/154 v7: https://lkml.org/lkml/2012/12/27/225 Hugh notes that this patch brings two problems, whose solution needs further support in mm/ksm.c, which follows in subsequent patches: 1) switching merge_across_nodes after running KSM is liable to oops on stale nodes still left over from the previous stable tree; 2) memory hotremove may migrate KSM pages, but there is no provision here for !merge_across_nodes to migrate nodes to the proper tree. Signed-off-by: Petr Holasek <pholasek@redhat.com> Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: rename page struct field helpersMel Gorman2013-02-2410-25/+25
| | | | | | | | | | | | | | | | | The function names page_xchg_last_nid(), page_last_nid() and reset_page_last_nid() were judged to be inconsistent so rename them to a struct_field_op style pattern. As it looked jarring to have reset_page_mapcount() and page_nid_reset_last() beside each other in memmap_init_zone(), this patch also renames reset_page_mapcount() to page_mapcount_reset(). There are others like init_page_count() but as it is used throughout the arch code a rename would likely cause more conflicts than it is worth. [akpm@linux-foundation.org: fix zcache] Signed-off-by: Mel Gorman <mgorman@suse.de> Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: avoid dangling reference count in creation failure.Glauber Costa2013-02-241-0/+2
| | | | | | | | | | | | | | | When use_hierarchy is enabled, we acquire an extra reference count in our parent during cgroup creation. We don't release it, though, if any failure exist in the creation process. Signed-off-by: Glauber Costa <glommer@parallels.com> Reported-by: Michal Hocko <mhocko@suse.cz> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: increment static branch right after limit setGlauber Costa2013-02-241-24/+7
| | | | | | | | | | | | | | | | | We were deferring the kmemcg static branch increment to a later time, due to a nasty dependency between the cpu_hotplug lock, taken by the jump label update, and the cgroup_lock. Now we no longer take the cgroup lock, and we can save ourselves the trouble. Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: replace cgroup_lock with memcg specific memcg_lockGlauber Costa2013-02-241-18/+21
| | | | | | | | | | | | | | | | | | | | After the preparation work done in earlier patches, the cgroup_lock can be trivially replaced with a memcg-specific lock. This is an automatic translation at every site where the values involved were queried. The sites where values are written, however, used to be naturally called under cgroup_lock. This is the case for instance in the css_online callback. For those, we now need to explicitly add the memcg lock. With this, all the calls to cgroup_lock outside cgroup core are gone. Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: fast hierarchy-aware child testGlauber Costa2013-02-241-7/+31
| | | | | | | | | | | | | | | | | | | | | | | | | Currently, we use cgroups' provided list of children to verify if it is safe to proceed with any value change that is dependent on the cgroup being empty. This is less than ideal, because it enforces a dependency over cgroup core that we would be better off without. The solution proposed here is to iterate over the child cgroups and if any is found that is already online, we bounce and return: we don't really care how many children we have, only if we have any. This is also made to be hierarchy aware. IOW, cgroups with hierarchy disabled, while they still exist, will be considered for the purpose of this interface as having no children. [akpm@linux-foundation.org: tweak comments] Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: split part of memcg creation to css_onlineGlauber Costa2013-02-241-22/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch is a preparatory work for later locking rework to get rid of big cgroup lock from memory controller code. The memory controller uses some tunables to adjust its operation. Those tunables are inherited from parent to children upon children intialization. For most of them, the value cannot be changed after the parent has a new children. cgroup core splits initialization in two phases: css_alloc and css_online. After css_alloc, the memory allocation and basic initialization are done. But the new group is not yet visible anywhere, not even for cgroup core code. It is only somewhere between css_alloc and css_online that it is inserted into the internal children lists. Copying tunable values in css_alloc will lead to inconsistent values: the children will copy the old parent values, that can change between the copy and the moment in which the groups is linked to any data structure that can indicate the presence of children. Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: prevent changes to move_charge_at_immigrate during task attachGlauber Costa2013-02-241-13/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In memcg, we use the cgroup_lock basically to synchronize against attaching new children to a cgroup. We do this because we rely on cgroup core to provide us with this information. We need to guarantee that upon child creation, our tunables are consistent. For those, the calls to cgroup_lock() all live in handlers like mem_cgroup_hierarchy_write(), where we change a tunable in the group that is hierarchy-related. For instance, the use_hierarchy flag cannot be changed if the cgroup already have children. Furthermore, those values are propagated from the parent to the child when a new child is created. So if we don't lock like this, we can end up with the following situation: A B memcg_css_alloc() mem_cgroup_hierarchy_write() copy use hierarchy from parent change use hierarchy in parent finish creation. This is mainly because during create, we are still not fully connected to the css tree. So all iterators and the such that we could use, will fail to show that the group has children. My observation is that all of creation can proceed in parallel with those tasks, except value assignment. So what this patch series does is to first move all value assignment that is dependent on parent values from css_alloc to css_online, where the iterators all work, and then we lock only the value assignment. This will guarantee that parent and children always have consistent values. Together with an online test, that can be derived from the observation that the refcount of an online memcg can be made to be always positive, we should be able to synchronize our side without the cgroup lock. This patch: Currently, we rely on the cgroup_lock() to prevent changes to move_charge_at_immigrate during task migration. However, this is only needed because the current strategy keeps checking this value throughout the whole process. Since all we need is serialization, one needs only to guarantee that whatever decision we made in the beginning of a specific migration is respected throughout the process. We can achieve this by just saving it in mc. By doing this, no kind of locking is needed. Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: reduce the size of struct memcg 244-fold.Glauber Costa2013-02-241-15/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to maintain all the memcg bookkeeping, we need per-node descriptors, which will in turn contain a per-zone descriptor. Because we want to statically allocate those, this array ends up being very big. Part of the reason is that we allocate something large enough to hold MAX_NUMNODES, the compile time constant that holds the maximum number of nodes we would ever consider. However, we can do better in some cases if the firmware help us. This is true for modern x86 machines; coincidentally one of the architectures in which MAX_NUMNODES tends to be very big. By using the firmware-provided maximum number of nodes instead of MAX_NUMNODES, we can reduce the memory footprint of struct memcg considerably. In the extreme case in which we have only one node, this reduces the size of the structure from ~ 64k to ~2k. This is particularly important because it means that we will no longer resort to the vmalloc area for the struct memcg on defconfigs. We also have enough room for an extra node and still be outside vmalloc. One also has to keep in mind that with the industry's ability to fit more processors in a die as fast as the FED prints money, a nodes = 2 configuration is already respectably big. [akpm@linux-foundation.org: add check for invalid nid, remove inline] Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ying Han <yinghan@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: init: report on last-nid information stored in page->flagsMel Gorman2013-02-241-12/+19
| | | | | | | | | | | | | | | | | | | Answering the question "how much space remains in the page->flags" is time-consuming. mminit_loglevel can help answer the question but it does not take last_nid information into account. This patch corrects it and while there it corrects the messages related to page flag usage, pgshifts and node/zone id. When applied the relevant output looks something like this but will depend on the kernel configuration. mminit::pageflags_layout_widths Section 0 Node 9 Zone 2 Lastnid 9 Flags 25 mminit::pageflags_layout_shifts Section 19 Node 9 Zone 2 Lastnid 9 mminit::pageflags_layout_pgshifts Section 0 Node 55 Zone 53 Lastnid 44 mminit::pageflags_layout_nodezoneid Node/Zone ID: 64 -> 53 mminit::pageflags_layout_usage location: 64 -> 44 layout 44 -> 25 unused 25 -> 0 page-flags Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: uninline page_xchg_last_nid()Mel Gorman2013-02-242-17/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | Andrew Morton pointed out that page_xchg_last_nid() and reset_page_last_nid() were "getting nuttily large" and asked that it be investigated. reset_page_last_nid() is on the page free path and it would be unfortunate to make that path more expensive than it needs to be. Due to the internal use of page_xchg_last_nid() it is already too expensive but fortunately, it should also be impossible for the page->flags to be updated in parallel when we call reset_page_last_nid(). Instead of unlining the function, it uses a simplier implementation that assumes no parallel updates and should now be sufficiently short for inlining. page_xchg_last_nid() is called in paths that are already quite expensive (splitting huge page, fault handling, migration) and it is reasonable to uninline. There was not really a good place to place the function but mm/mmzone.c was the closest fit IMO. This patch saved 128 bytes of text in the vmlinux file for the kernel configuration I used for testing automatic NUMA balancing. Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: clean up swap accounting initialization codeMichal Hocko2013-02-241-18/+12
| | | | | | | | | | | | | | | | | | | | Memcg swap accounting is currently enabled by enable_swap_cgroup when the root cgroup is created. mem_cgroup_init acts as a memcg subsystem initializer which sounds like a much better place for enable_swap_cgroup as well. We already register memsw files from there so it makes a lot of sense to merge those two into a single enable_swap_cgroup function. This patch doesn't introduce any semantic changes. Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Zhouping Liu <zliu@redhat.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Li Zefan <lizefan@huawei.com> Cc: CAI Qian <caiqian@redhat.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* memcg: do not create memsw files if swap accounting is disabledMichal Hocko2013-02-241-40/+54
| | | | | | | | | | | | | | | | | | | | | | | | | | | Zhouping Liu has reported that memsw files are exported even though swap accounting is runtime disabled if MEMCG_SWAP is enabled. This behavior has been introduced by commit af36f906c0f4 ("memcg: always create memsw files if CGROUP_MEM_RES_CTLR_SWAP") and it causes any attempt to open the file to return EOPNOTSUPP. Although EOPNOTSUPP should say be clear that memsw operations are not supported in the given configuration it is fair to say that this behavior could be quite confusing. Let's tear memsw files out of default cgroup files and add them only if the swap accounting is really enabled (either by MEMCG_SWAP_ENABLED or swapaccount=1 boot parameter). We can hook into mem_cgroup_init which is called when the memcg subsystem is initialized and which happens after boot command line is processed. Signed-off-by: Michal Hocko <mhocko@suse.cz> Reported-by: Zhouping Liu <zliu@redhat.com> Tested-by: Zhouping Liu <zliu@redhat.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Li Zefan <lizefan@huawei.com> Cc: CAI Qian <caiqian@redhat.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* page-writeback.c: subtract min_free_kbytes from dirtyable memoryPaul Szabo2013-02-244-2/+6
| | | | | | | | | | | | | | | When calculating amount of dirtyable memory, min_free_kbytes should be subtracted because it is not intended for dirty pages. Addresses http://bugs.debian.org/695182 [akpm@linux-foundation.org: fix up min_free_kbytes extern declarations] [akpm@linux-foundation.org: fix min() warning] Signed-off-by: Paul Szabo <psz@maths.usyd.edu.au> Acked-by: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/rmap: rename anon_vma_unlock() => anon_vma_unlock_write()Konstantin Khlebnikov2013-02-246-11/+11
| | | | | | | | | | | | | | | | | The comment in commit 4fc3f1d66b1e ("mm/rmap, migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable") says: | Rename anon_vma_[un]lock() => anon_vma_[un]lock_write(), | to make it clearer that it's an exclusive write-lock in | that case - suggested by Rik van Riel. But that commit renames only anon_vma_lock() Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Ingo Molnar <mingo@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* swap: add per-partition lock for swapfileShaohua Li2013-02-248-60/+145
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | swap_lock is heavily contended when I test swap to 3 fast SSD (even slightly slower than swap to 2 such SSD). The main contention comes from swap_info_get(). This patch tries to fix the gap with adding a new per-partition lock. Global data like nr_swapfiles, total_swap_pages, least_priority and swap_list are still protected by swap_lock. nr_swap_pages is an atomic now, it can be changed without swap_lock. In theory, it's possible get_swap_page() finds no swap pages but actually there are free swap pages. But sounds not a big problem. Accessing partition specific data (like scan_swap_map and so on) is only protected by swap_info_struct.lock. Changing swap_info_struct.flags need hold swap_lock and swap_info_struct.lock, because scan_scan_map() will check it. read the flags is ok with either the locks hold. If both swap_lock and swap_info_struct.lock must be hold, we always hold the former first to avoid deadlock. swap_entry_free() can change swap_list. To delete that code, we add a new highest_priority_index. Whenever get_swap_page() is called, we check it. If it's valid, we use it. It's a pity get_swap_page() still holds swap_lock(). But in practice, swap_lock() isn't heavily contended in my test with this patch (or I can say there are other much more heavier bottlenecks like TLB flush). And BTW, looks get_swap_page() doesn't really need the lock. We never free swap_info[] and we check SWAP_WRITEOK flag. The only risk without the lock is we could swapout to some low priority swap, but we can quickly recover after several rounds of swap, so sounds not a big deal to me. But I'd prefer to fix this if it's a real problem. "swap: make each swap partition have one address_space" improved the swapout speed from 1.7G/s to 2G/s. This patch further improves the speed to 2.3G/s, so around 15% improvement. It's a multi-process test, so TLB flush isn't the biggest bottleneck before the patches. [arnd@arndb.de: fix it for nommu] [hughd@google.com: add missing unlock] [minchan@kernel.org: get rid of lockdep whinge on sys_swapon] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* swap: make each swap partition have one address_spaceShaohua Li2013-02-248-34/+67
| | | | | | | | | | | | | | | | | When I use several fast SSD to do swap, swapper_space.tree_lock is heavily contended. This makes each swap partition have one address_space to reduce the lock contention. There is an array of address_space for swap. The swap entry type is the index to the array. In my test with 3 SSD, this increases the swapout throughput 20%. [akpm@linux-foundation.org: revert unneeded change to __add_to_swap_cache] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Hugh Dickins <hughd@google.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: don't inline page_mapping()Shaohua Li2013-02-242-12/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | According to akpm, this saves 1/2k text and makes things simple for the next patch. Numbers from Minchan: add/remove: 1/0 grow/shrink: 6/22 up/down: 92/-516 (-424) function old new delta page_mapping - 48 +48 do_task_stat 2292 2308 +16 page_remove_rmap 240 248 +8 load_elf_binary 4500 4508 +8 update_queue 532 536 +4 scsi_probe_and_add_lun 2892 2896 +4 lookup_fast 644 648 +4 vcs_read 1040 1036 -4 __ip_route_output_key 1904 1900 -4 ip_route_input_noref 2508 2500 -8 shmem_file_aio_read 784 772 -12 __isolate_lru_page 272 256 -16 shmem_replace_page 708 688 -20 mark_buffer_dirty 228 208 -20 __set_page_dirty_buffers 240 220 -20 __remove_mapping 276 256 -20 update_mmu_cache 500 476 -24 set_page_dirty_balance 92 68 -24 set_page_dirty 172 148 -24 page_evictable 88 64 -24 page_cache_pipe_buf_steal 248 224 -24 clear_page_dirty_for_io 340 316 -24 test_set_page_writeback 400 372 -28 test_clear_page_writeback 516 488 -28 invalidate_inode_page 156 128 -28 page_mkclean 432 400 -32 flush_dcache_page 360 328 -32 __set_page_dirty_nobuffers 324 280 -44 shrink_page_list 2412 2356 -56 Signed-off-by: Shaohua Li <shli@fusionio.com> Suggested-by: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <hughd@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: numa: cleanup flow of transhuge page migrationHugh Dickins2013-02-242-71/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When correcting commit 04fa5d6a6547 ("mm: migrate: check page_count of THP before migrating") Hugh Dickins noted that the control flow for transhuge migration was difficult to follow. Unconditionally calling put_page() in numamigrate_isolate_page() made the failure paths of both migrate_misplaced_transhuge_page() and migrate_misplaced_page() more complex that they should be. Further, he was extremely wary that an unlock_page() should ever happen after a put_page() even if the put_page() should never be the final put_page. Hugh implemented the following cleanup to simplify the path by calling putback_lru_page() inside numamigrate_isolate_page() if it failed to isolate and always calling unlock_page() within migrate_misplaced_transhuge_page(). There is no functional change after this patch is applied but the code is easier to follow and unlock_page() always happens before put_page(). [mgorman@suse.de: changelog only] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Simon Jeons <simon.jeons@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fold page->_last_nid into page->flags where possiblePeter Zijlstra2013-02-244-10/+62
| | | | | | | | | | | | | | | | | | | | page->_last_nid fits into page->flags on 64-bit. The unlikely 32-bit NUMA configuration with NUMA Balancing will still need an extra page field. As Peter notes "Completely dropping 32bit support for CONFIG_NUMA_BALANCING would simplify things, but it would also remove the warning if we grow enough 64bit only page-flags to push the last-cpu out." [mgorman@suse.de: minor modifications] Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Simon Jeons <simon.jeons@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: move page flags layout to separate headerPeter Zijlstra2013-02-244-61/+73
| | | | | | | | | | | | | | | | | This is a preparation patch for moving page->_last_nid into page->flags that moves page flag layout information to a separate header. This patch is necessary because otherwise there would be a circular dependency between mm_types.h and mm.h. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Simon Jeons <simon.jeons@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: numa: handle side-effects in count_vm_numa_events() for ↵Mel Gorman2013-02-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | !CONFIG_NUMA_BALANCING The current definitions for count_vm_numa_events() is wrong for !CONFIG_NUMA_BALANCING as the following would miss the side-effect. count_vm_numa_events(NUMA_FOO, bar++); There are no such users of count_vm_numa_events() but this patch fixes it as it is a potential pitfall. Ideally both would be converted to static inline but NUMA_PTE_UPDATES is not defined if !CONFIG_NUMA_BALANCING and creating dummy constants just to have a static inline would be similarly clumsy. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Simon Jeons <simon.jeons@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: numa: take THP into account when migrating pages for NUMA balancingMel Gorman2013-02-241-2/+4
| | | | | | | | | | | | | | | | | | | | | | Wanpeng Li pointed out that numamigrate_isolate_page() assumes that only one base page is being migrated when in fact it can also be checking THP. The consequences are that a migration will be attempted when a target node is nearly full and fail later. It's unlikely to be user-visible but it should be fixed. While we are there, migrate_balanced_pgdat() should treat nr_migrate_pages as an unsigned long as it is treated as a watermark. Signed-off-by: Mel Gorman <mgorman@suse.de> Suggested-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Simon Jeons <simon.jeons@gmail.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: numa: fix minor typo in numa_next_scanMel Gorman2013-02-241-3/+3
| | | | | | | | | | | | | | s/me/be/ and clarify the comment a bit when we're changing it anyway. Signed-off-by: Mel Gorman <mgorman@suse.de> Suggested-by: Simon Jeons <simon.jeons@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove unused memclear_highpage_flush()Kirill A. Shutemov2013-02-241-6/+0
| | | | | | Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* usb: forbid memory allocation with I/O during bus resetMing Lei2013-02-241-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If one storage interface or usb network interface(iSCSI case) exists in current configuration, memory allocation with GFP_KERNEL during usb_device_reset() might trigger I/O transfer on the storage interface itself and cause deadlock because the 'us->dev_mutex' is held in .pre_reset() and the storage interface can't do I/O transfer when the reset is triggered by other interface, or the error handling can't be completed if the reset is triggered by the storage itself (error handling path). Signed-off-by: Ming Lei <ming.lei@canonical.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: David Decotigny <david.decotigny@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jens Axboe <axboe@kernel.dk> Cc: Minchan Kim <minchan@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Oliver Neukum <oneukum@suse.de> Reviewed-by: Jiri Kosina <jkosina@suse.cz> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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