- 09 10月, 2012 2 次提交
-
-
由 Konstantin Khlebnikov 提交于
Merge VM_INSERTPAGE into VM_MIXEDMAP. VM_MIXEDMAP VMA can mix pure-pfn ptes, special ptes and normal ptes. Now copy_page_range() always copies VM_MIXEDMAP VMA on fork like VM_PFNMAP. If driver populates whole VMA at mmap() it probably not expects page-faults. This patch removes special check from vma_wants_writenotify() which disables pages write tracking for VMA populated via vm_instert_page(). BDI below mapped file should not use dirty-accounting, moreover do_wp_page() can handle this. vm_insert_page() still marks vma after first usage. Usually it is called from f_op->mmap() handler under mm->mmap_sem write-lock, so it able to change vma->vm_flags. Caller must set VM_MIXEDMAP at mmap time if it wants to call this function from other places, for example from page-fault handler. Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Konstantin Khlebnikov 提交于
Combine several arch-specific vma flags into one. before patch: 0x00000200 0x01000000 0x20000000 0x40000000 x86 VM_NOHUGEPAGE VM_HUGEPAGE - VM_PAT powerpc - - VM_SAO - parisc VM_GROWSUP - - - ia64 VM_GROWSUP - - - nommu - VM_MAPPED_COPY - - others - - - - after patch: 0x00000200 0x01000000 0x20000000 0x40000000 x86 - VM_PAT VM_HUGEPAGE VM_NOHUGEPAGE powerpc - VM_SAO - - parisc - VM_GROWSUP - - ia64 - VM_GROWSUP - - nommu - VM_MAPPED_COPY - - others - VM_ARCH_1 - - And voila! One completely free bit. Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 22 3月, 2012 1 次提交
-
-
由 Bob Liu 提交于
There are multiple places which perform the same check. Add a new find_mergeable_vma() to handle this. Signed-off-by: NBob Liu <lliubbo@gmail.com> Acked-by: NHugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 20 3月, 2012 1 次提交
-
-
由 Cong Wang 提交于
Signed-off-by: NCong Wang <amwang@redhat.com>
-
- 06 3月, 2012 1 次提交
-
-
由 Hugh Dickins 提交于
When moving tasks from old memcg (with move_charge_at_immigrate on new memcg), followed by removal of old memcg, hit General Protection Fault in mem_cgroup_lru_del_list() (called from release_pages called from free_pages_and_swap_cache from tlb_flush_mmu from tlb_finish_mmu from exit_mmap from mmput from exit_mm from do_exit). Somewhat reproducible, takes a few hours: the old struct mem_cgroup has been freed and poisoned by SLAB_DEBUG, but mem_cgroup_lru_del_list() is still trying to update its stats, and take page off lru before freeing. A task, or a charge, or a page on lru: each secures a memcg against removal. In this case, the last task has been moved out of the old memcg, and it is exiting: anonymous pages are uncharged one by one from the memcg, as they are zapped from its pagetables, so the charge gets down to 0; but the pages themselves are queued in an mmu_gather for freeing. Most of those pages will be on lru (and force_empty is careful to lru_add_drain_all, to add pages from pagevec to lru first), but not necessarily all: perhaps some have been isolated for page reclaim, perhaps some isolated for other reasons. So, force_empty may find no task, no charge and no page on lru, and let the removal proceed. There would still be no problem if these pages were immediately freed; but typically (and the put_page_testzero protocol demands it) they have to be added back to lru before they are found freeable, then removed from lru and freed. We don't see the issue when adding, because the mem_cgroup_iter() loops keep their own reference to the memcg being scanned; but when it comes to mem_cgroup_lru_del_list(). I believe this was not an issue in v3.2: there, PageCgroupAcctLRU and PageCgroupUsed flags were used (like a trick with mirrors) to deflect view of pc->mem_cgroup to the stable root_mem_cgroup when neither set. 38c5d72f ("memcg: simplify LRU handling by new rule") mercifully removed those convolutions, but left this General Protection Fault. But it's surprisingly easy to restore the old behaviour: just check PageCgroupUsed in mem_cgroup_lru_add_list() (which decides on which lruvec to add), and reset pc to root_mem_cgroup if page is uncharged. A risky change? just going back to how it worked before; testing, and an audit of uses of pc->mem_cgroup, show no problem. And there's a nice bonus: with mem_cgroup_lru_add_list() itself making sure that an uncharged page goes to root lru, mem_cgroup_reset_owner() no longer has any purpose, and we can safely revert 4e5f01c2 ("memcg: clear pc->mem_cgroup if necessary"). Calling update_page_reclaim_stat() after add_page_to_lru_list() in swap.c is not strictly necessary: the lru_lock there, with RCU before memcg structures are freed, makes mem_cgroup_get_reclaim_stat_from_page safe without that; but it seems cleaner to rely on one dependency less. Signed-off-by: NHugh Dickins <hughd@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 13 1月, 2012 1 次提交
-
-
由 KAMEZAWA Hiroyuki 提交于
This is a preparation before removing a flag PCG_ACCT_LRU in page_cgroup and reducing atomic ops/complexity in memcg LRU handling. In some cases, pages are added to lru before charge to memcg and pages are not classfied to memory cgroup at lru addtion. Now, the lru where the page should be added is determined a bit in page_cgroup->flags and pc->mem_cgroup. I'd like to remove the check of flag. To handle the case pc->mem_cgroup may contain stale pointers if pages are added to LRU before classification. This patch resets pc->mem_cgroup to root_mem_cgroup before lru additions. [akpm@linux-foundation.org: fix CONFIG_CGROUP_MEM_CONT=n build] [hughd@google.com: fix CONFIG_CGROUP_MEM_RES_CTLR=y CONFIG_CGROUP_MEM_RES_CTLR_SWAP=n build] [akpm@linux-foundation.org: ksm.c needs memcontrol.h, per Michal] [hughd@google.com: stop oops in mem_cgroup_reset_owner()] [hughd@google.com: fix page migration to reset_owner] Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Miklos Szeredi <mszeredi@suse.cz> Acked-by: NMichal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Ying Han <yinghan@google.com> Signed-off-by: NHugh Dickins <hughd@google.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 01 11月, 2011 1 次提交
-
-
由 David Rientjes 提交于
test_set_oom_score_adj() was introduced in 72788c38 ("oom: replace PF_OOM_ORIGIN with toggling oom_score_adj") to temporarily elevate current's oom_score_adj for ksm and swapoff without requiring an additional per-process flag. Using that function to both set oom_score_adj to OOM_SCORE_ADJ_MAX and then reinstate the previous value is racy since it's possible that userspace can set the value to something else itself before the old value is reinstated. That results in userspace setting current's oom_score_adj to a different value and then the kernel immediately setting it back to its previous value without notification. To fix this, a new compare_swap_oom_score_adj() function is introduced with the same semantics as the compare and swap CAS instruction, or CMPXCHG on x86. It is used to reinstate the previous value of oom_score_adj if and only if the present value is the same as the old value. Signed-off-by: NDavid Rientjes <rientjes@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ying Han <yinghan@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 16 6月, 2011 1 次提交
-
-
由 Hugh Dickins 提交于
Andrea Righi reported a case where an exiting task can race against ksmd::scan_get_next_rmap_item (http://lkml.org/lkml/2011/6/1/742) easily triggering a NULL pointer dereference in ksmd. ksm_scan.mm_slot == &ksm_mm_head with only one registered mm CPU 1 (__ksm_exit) CPU 2 (scan_get_next_rmap_item) list_empty() is false lock slot == &ksm_mm_head list_del(slot->mm_list) (list now empty) unlock lock slot = list_entry(slot->mm_list.next) (list is empty, so slot is still ksm_mm_head) unlock slot->mm == NULL ... Oops Close this race by revalidating that the new slot is not simply the list head again. Andrea's test case: #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> #define BUFSIZE getpagesize() int main(int argc, char **argv) { void *ptr; if (posix_memalign(&ptr, getpagesize(), BUFSIZE) < 0) { perror("posix_memalign"); exit(1); } if (madvise(ptr, BUFSIZE, MADV_MERGEABLE) < 0) { perror("madvise"); exit(1); } *(char *)NULL = 0; return 0; } Reported-by: NAndrea Righi <andrea@betterlinux.com> Tested-by: NAndrea Righi <andrea@betterlinux.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NHugh Dickins <hughd@google.com> Signed-off-by: NChris Wright <chrisw@sous-sol.org> Cc: <stable@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 25 5月, 2011 1 次提交
-
-
由 David Rientjes 提交于
There's a kernel-wide shortage of per-process flags, so it's always helpful to trim one when possible without incurring a significant penalty. It's even more important when you're planning on adding a per- process flag yourself, which I plan to do shortly for transparent hugepages. PF_OOM_ORIGIN is used by ksm and swapoff to prefer current since it has a tendency to allocate large amounts of memory and should be preferred for killing over other tasks. We'd rather immediately kill the task making the errant syscall rather than penalizing an innocent task. This patch removes PF_OOM_ORIGIN since its behavior is equivalent to setting the process's oom_score_adj to OOM_SCORE_ADJ_MAX. The process's old oom_score_adj is stored and then set to OOM_SCORE_ADJ_MAX during the time it used to have PF_OOM_ORIGIN. The old value is then reinstated when the process should no longer be considered a high priority for oom killing. Signed-off-by: NDavid Rientjes <rientjes@google.com> Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: NMinchan Kim <minchan.kim@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Izik Eidus <ieidus@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 31 3月, 2011 1 次提交
-
-
由 Lucas De Marchi 提交于
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>
-
- 23 3月, 2011 1 次提交
-
-
由 Peter Zijlstra 提交于
The normal code pattern used in the kernel is: get/put. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: NHugh Dickins <hughd@google.com> Reviewed-by: NRik van Riel <riel@redhat.com> Acked-by: NMel Gorman <mel@csn.ul.ie> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 14 1月, 2011 6 次提交
-
-
由 Hugh Dickins 提交于
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: NHugh Dickins <hughd@google.com> Reported-by: NCAI Qian <caiqian@redhat.com> Cc:Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Andrea Arcangeli 提交于
Cleanup some code with common compound_trans_head helper. Signed-off-by: NAndrea 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: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Andrea Arcangeli 提交于
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: NAndrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Andrea Arcangeli 提交于
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: NAndrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Andrea Arcangeli 提交于
Skip transhuge pages in ksm for now. Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com> Reviewed-by: NRik van Riel <riel@redhat.com> Acked-by: NMel Gorman <mel@csn.ul.ie> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
When a swapcache page is replaced by a ksm page, it's best to free that swap immediately. Reported-by: NAndrea Arcangeli <aarcange@redhat.com> Signed-off-by: NHugh Dickins <hughd@google.com> Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 03 12月, 2010 1 次提交
-
-
由 KOSAKI Motohiro 提交于
commit 62b61f61 ("ksm: memory hotremove migration only") caused the following new lockdep warning. ======================================================= [ INFO: possible circular locking dependency detected ] ------------------------------------------------------- bash/1621 is trying to acquire lock: ((memory_chain).rwsem){.+.+.+}, at: [<ffffffff81079339>] __blocking_notifier_call_chain+0x69/0xc0 but task is already holding lock: (ksm_thread_mutex){+.+.+.}, at: [<ffffffff8113a3aa>] ksm_memory_callback+0x3a/0xc0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (ksm_thread_mutex){+.+.+.}: [<ffffffff8108b70a>] lock_acquire+0xaa/0x140 [<ffffffff81505d74>] __mutex_lock_common+0x44/0x3f0 [<ffffffff81506228>] mutex_lock_nested+0x48/0x60 [<ffffffff8113a3aa>] ksm_memory_callback+0x3a/0xc0 [<ffffffff8150c21c>] notifier_call_chain+0x8c/0xe0 [<ffffffff8107934e>] __blocking_notifier_call_chain+0x7e/0xc0 [<ffffffff810793a6>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813afbfb>] memory_notify+0x1b/0x20 [<ffffffff81141b7c>] remove_memory+0x1cc/0x5f0 [<ffffffff813af53d>] memory_block_change_state+0xfd/0x1a0 [<ffffffff813afd62>] store_mem_state+0xe2/0xf0 [<ffffffff813a0bb0>] sysdev_store+0x20/0x30 [<ffffffff811bc116>] sysfs_write_file+0xe6/0x170 [<ffffffff8114f398>] vfs_write+0xc8/0x190 [<ffffffff8114fc14>] sys_write+0x54/0x90 [<ffffffff810028b2>] system_call_fastpath+0x16/0x1b -> #0 ((memory_chain).rwsem){.+.+.+}: [<ffffffff8108b5ba>] __lock_acquire+0x155a/0x1600 [<ffffffff8108b70a>] lock_acquire+0xaa/0x140 [<ffffffff81506601>] down_read+0x51/0xa0 [<ffffffff81079339>] __blocking_notifier_call_chain+0x69/0xc0 [<ffffffff810793a6>] blocking_notifier_call_chain+0x16/0x20 [<ffffffff813afbfb>] memory_notify+0x1b/0x20 [<ffffffff81141f1e>] remove_memory+0x56e/0x5f0 [<ffffffff813af53d>] memory_block_change_state+0xfd/0x1a0 [<ffffffff813afd62>] store_mem_state+0xe2/0xf0 [<ffffffff813a0bb0>] sysdev_store+0x20/0x30 [<ffffffff811bc116>] sysfs_write_file+0xe6/0x170 [<ffffffff8114f398>] vfs_write+0xc8/0x190 [<ffffffff8114fc14>] sys_write+0x54/0x90 [<ffffffff810028b2>] system_call_fastpath+0x16/0x1b But it's a false positive. Both memory_chain.rwsem and ksm_thread_mutex have an outer lock (mem_hotplug_mutex). So they cannot deadlock. Thus, This patch annotate ksm_thread_mutex is not deadlock source. [akpm@linux-foundation.org: update comment, from Hugh] Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: NHugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 05 10月, 2010 1 次提交
-
-
由 Hugh Dickins 提交于
Building under memory pressure, with KSM on 2.6.36-rc5, collapsed with an internal compiler error: typically indicating an error in swapping. Perhaps there's a timing issue which makes it now more likely, perhaps it's just a long time since I tried for so long: this bug goes back to KSM swapping in 2.6.33. Notice how reuse_swap_page() allows an exclusive page to be reused, but only does SetPageDirty if it can delete it from swap cache right then - if it's currently under Writeback, it has to be left in cache and we don't SetPageDirty, but the page can be reused. Fine, the dirty bit will get set in the pte; but notice how zap_pte_range() does not bother to transfer pte_dirty to page_dirty when unmapping a PageAnon. If KSM chooses to share such a page, it will look like a clean copy of swapcache, and not be written out to swap when its memory is needed; then stale data read back from swap when it's needed again. We could fix this in reuse_swap_page() (or even refuse to reuse a page under writeback), but it's more honest to fix my oversight in KSM's write_protect_page(). Several days of testing on three machines confirms that this fixes the issue they showed. Signed-off-by: NHugh Dickins <hughd@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: stable@kernel.org Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 10 9月, 2010 1 次提交
-
-
由 Andrea Arcangeli 提交于
The pte_same check is reliable only if the swap entry remains pinned (by the page lock on swapcache). We've also to ensure the swapcache isn't removed before we take the lock as try_to_free_swap won't care about the page pin. One of the possible impacts of this patch is that a KSM-shared page can point to the anon_vma of another process, which could exit before the page is freed. This can leave a page with a pointer to a recycled anon_vma object, or worse, a pointer to something that is no longer an anon_vma. [riel@redhat.com: changelog help] Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com> Acked-by: NHugh Dickins <hughd@google.com> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: <stable@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 10 8月, 2010 4 次提交
-
-
由 Lai Jiangshan 提交于
Use compile-allocated memory instead of dynamic allocated memory for mm_slots_hash. Use hash_ptr() instead divisions for bucket calculation. Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: NIzik Eidus <ieidus@redhat.com> Cc: Avi Kivity <avi@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Rik van Riel 提交于
KSM reference counts can cause an anon_vma to exist after the processe it belongs to have already exited. Because the anon_vma lock now lives in the root anon_vma, we need to ensure that the root anon_vma stays around until after all the "child" anon_vmas have been freed. The obvious way to do this is to have a "child" anon_vma take a reference to the root in anon_vma_fork. When the anon_vma is freed at munmap or process exit, we drop the refcount in anon_vma_unlink and possibly free the root anon_vma. The KSM anon_vma reference count function also needs to be modified to deal with the possibility of freeing 2 levels of anon_vma. The easiest way to do this is to break out the KSM magic and make it generic. When compiling without CONFIG_KSM, this code is compiled out. Signed-off-by: NRik van Riel <riel@redhat.com> Tested-by: NLarry Woodman <lwoodman@redhat.com> Acked-by: NLarry Woodman <lwoodman@redhat.com> Reviewed-by: NMinchan Kim <minchan.kim@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: NMel Gorman <mel@csn.ul.ie> Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Tested-by: NDave Young <hidave.darkstar@gmail.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Rik van Riel 提交于
Always (and only) lock the root (oldest) anon_vma whenever we do something in an anon_vma. The recently introduced anon_vma scalability is due to the rmap code scanning only the VMAs that need to be scanned. Many common operations still took the anon_vma lock on the root anon_vma, so always taking that lock is not expected to introduce any scalability issues. However, always taking the same lock does mean we only need to take one lock, which means rmap_walk on pages from any anon_vma in the vma is excluded from occurring during an munmap, expand_stack or other operation that needs to exclude rmap_walk and similar functions. Also add the proper locking to vma_adjust. Signed-off-by: NRik van Riel <riel@redhat.com> Tested-by: NLarry Woodman <lwoodman@redhat.com> Acked-by: NLarry Woodman <lwoodman@redhat.com> Reviewed-by: NMinchan Kim <minchan.kim@gmail.com> Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: NMel Gorman <mel@csn.ul.ie> Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Rik van Riel 提交于
Subsitute a direct call of spin_lock(anon_vma->lock) with an inline function doing exactly the same. This makes it easier to do the substitution to the root anon_vma lock in a following patch. We will deal with the handful of special locks (nested, dec_and_lock, etc) separately. Signed-off-by: NRik van Riel <riel@redhat.com> Acked-by: NMel Gorman <mel@csn.ul.ie> Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Tested-by: NLarry Woodman <lwoodman@redhat.com> Acked-by: NLarry Woodman <lwoodman@redhat.com> Reviewed-by: NMinchan Kim <minchan.kim@gmail.com> Acked-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 25 5月, 2010 1 次提交
-
-
由 Mel Gorman 提交于
For clarity of review, KSM and page migration have separate refcounts on the anon_vma. While clear, this is a waste of memory. This patch gets KSM and page migration to share their toys in a spirit of harmony. Signed-off-by: NMel Gorman <mel@csn.ul.ie> Reviewed-by: NMinchan Kim <minchan.kim@gmail.com> Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: NChristoph Lameter <cl@linux-foundation.org> Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 25 4月, 2010 1 次提交
-
-
由 Dan Carpenter 提交于
The follow_page() function can potentially return -EFAULT so I added checks for this. Also I silenced an uninitialized variable warning on my version of gcc (version 4.3.2). Signed-off-by: NDan Carpenter <error27@gmail.com> Acked-by: NRik van Riel <riel@redhat.com> Acked-by: NIzik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 25 3月, 2010 1 次提交
-
-
由 Robin Holt 提交于
ksm.c's write_protect_page implements a lockless means of verifying a page does not have any users of the page which are not accounted for via other kernel tracking means. It does this by removing the writable pte with TLB flushes, checking the page_count against the total known users, and then using set_pte_at_notify to make it a read-only entry. An unneeded mmu_notifier callout is made in the case where the known users does not match the page_count. In that event, we are inserting the identical pte and there is no need for the set_pte_at_notify, but rather the simpler set_pte_at suffices. Signed-off-by: NRobin Holt <holt@sgi.com> Acked-by: NIzik Eidus <ieidus@redhat.com> Acked-by: NAndrea Arcangeli <aarcange@redhat.com> Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 07 3月, 2010 1 次提交
-
-
由 Rik van Riel 提交于
The old anon_vma code can lead to scalability issues with heavily forking workloads. Specifically, each anon_vma will be shared between the parent process and all its child processes. In a workload with 1000 child processes and a VMA with 1000 anonymous pages per process that get COWed, this leads to a system with a million anonymous pages in the same anon_vma, each of which is mapped in just one of the 1000 processes. However, the current rmap code needs to walk them all, leading to O(N) scanning complexity for each page. This can result in systems where one CPU is walking the page tables of 1000 processes in page_referenced_one, while all other CPUs are stuck on the anon_vma lock. This leads to catastrophic failure for a benchmark like AIM7, where the total number of processes can reach in the tens of thousands. Real workloads are still a factor 10 less process intensive than AIM7, but they are catching up. This patch changes the way anon_vmas and VMAs are linked, which allows us to associate multiple anon_vmas with a VMA. At fork time, each child process gets its own anon_vmas, in which its COWed pages will be instantiated. The parents' anon_vma is also linked to the VMA, because non-COWed pages could be present in any of the children. This reduces rmap scanning complexity to O(1) for the pages of the 1000 child processes, with O(N) complexity for at most 1/N pages in the system. This reduces the average scanning cost in heavily forking workloads from O(N) to 2. The only real complexity in this patch stems from the fact that linking a VMA to anon_vmas now involves memory allocations. This means vma_adjust can fail, if it needs to attach a VMA to anon_vma structures. This in turn means error handling needs to be added to the calling functions. A second source of complexity is that, because there can be multiple anon_vmas, the anon_vma linking in vma_adjust can no longer be done under "the" anon_vma lock. To prevent the rmap code from walking up an incomplete VMA, this patch introduces the VM_LOCK_RMAP VMA flag. This bit flag uses the same slot as the NOMMU VM_MAPPED_COPY, with an ifdef in mm.h to make sure it is impossible to compile a kernel that needs both symbolic values for the same bitflag. Some test results: Without the anon_vma changes, when AIM7 hits around 9.7k users (on a test box with 16GB RAM and not quite enough IO), the system ends up running >99% in system time, with every CPU on the same anon_vma lock in the pageout code. With these changes, AIM7 hits the cross-over point around 29.7k users. This happens with ~99% IO wait time, there never seems to be any spike in system time. The anon_vma lock contention appears to be resolved. [akpm@linux-foundation.org: cleanups] Signed-off-by: NRik van Riel <riel@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
- 16 12月, 2009 12 次提交
-
-
由 Hugh Dickins 提交于
Now that ksm pages are swappable, and the known holes plugged, remove mention of unswappable kernel pages from KSM documentation and comments. Remove the totalram_pages/4 initialization of max_kernel_pages. In fact, remove max_kernel_pages altogether - we can reinstate it if removal turns out to break someone's script; but if we later want to limit KSM's memory usage, limiting the stable nodes would not be an effective approach. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
The previous patch enables page migration of ksm pages, but that soon gets into trouble: not surprising, since we're using the ksm page lock to lock operations on its stable_node, but page migration switches the page whose lock is to be used for that. Another layer of locking would fix it, but do we need that yet? Do we actually need page migration of ksm pages? Yes, memory hotremove needs to offline sections of memory: and since we stopped allocating ksm pages with GFP_HIGHUSER, they will tend to be GFP_HIGHUSER_MOVABLE candidates for migration. But KSM is currently unconscious of NUMA issues, happily merging pages from different NUMA nodes: at present the rule must be, not to use MADV_MERGEABLE where you care about NUMA. So no, NUMA page migration of ksm pages does not make sense yet. So, to complete support for ksm swapping we need to make hotremove safe. ksm_memory_callback() take ksm_thread_mutex when MEM_GOING_OFFLINE and release it when MEM_OFFLINE or MEM_CANCEL_OFFLINE. But if mapped pages are freed before migration reaches them, stable_nodes may be left still pointing to struct pages which have been removed from the system: the stable_node needs to identify a page by pfn rather than page pointer, then it can safely prune them when MEM_OFFLINE. And make NUMA migration skip PageKsm pages where it skips PageReserved. But it's only when we reach unmap_and_move() that the page lock is taken and we can be sure that raised pagecount has prevented a PageAnon from being upgraded: so add offlining arg to migrate_pages(), to migrate ksm page when offlining (has sufficient locking) but reject it otherwise. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
A side-effect of making ksm pages swappable is that they have to be placed on the LRUs: which then exposes them to isolate_lru_page() and hence to page migration. Add rmap_walk() for remove_migration_ptes() to use: rmap_walk_anon() and rmap_walk_file() in rmap.c, but rmap_walk_ksm() in ksm.c. Perhaps some consolidation with existing code is possible, but don't attempt that yet (try_to_unmap needs to handle nonlinears, but migration pte removal does not). rmap_walk() is sadly less general than it appears: rmap_walk_anon(), like remove_anon_migration_ptes() which it replaces, avoids calling page_lock_anon_vma(), because that includes a page_mapped() test which fails when all migration ptes are in place. That was valid when NUMA page migration was introduced (holding mmap_sem provided the missing guarantee that anon_vma's slab had not already been destroyed), but I believe not valid in the memory hotremove case added since. For now do the same as before, and consider the best way to fix that unlikely race later on. When fixed, we can probably use rmap_walk() on hwpoisoned ksm pages too: for now, they remain among hwpoison's various exceptions (its PageKsm test comes before the page is locked, but its page_lock_anon_vma fails safely if an anon gets upgraded). Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
When ksm pages were unswappable, it made no sense to include them in mem cgroup accounting; but now that they are swappable (although I see no strict logical connection) the principle of least surprise implies that they should be accounted (with the usual dissatisfaction, that a shared page is accounted to only one of the cgroups using it). This patch was intended to add mem cgroup accounting where necessary; but turned inside out, it now avoids allocating a ksm page, instead upgrading an anon page to ksm - which brings its existing mem cgroup accounting with it. Thus mem cgroups don't appear in the patch at all. This upgrade from PageAnon to PageKsm takes place under page lock (via a somewhat hacky NULL kpage interface), and audit showed only one place which needed to cope with the race - page_referenced() is sometimes used without page lock, so page_lock_anon_vma() needs an ACCESS_ONCE() to be sure of getting anon_vma and flags together (no problem if the page goes ksm an instant after, the integrity of that anon_vma list is unaffected). Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
There's a lamentable flaw in KSM swapping: the stable_node holds a reference to the ksm page, so the page to be freed cannot actually be freed until ksmd works its way around to removing the last rmap_item from its stable_node. Which in some configurations may take minutes: not quite responsive enough for memory reclaim. And we don't want to twist KSM and its locking more tightly into the rest of mm. What a pity. But although the stable_node needs to hold a pointer to the ksm page, does it actually need to raise the reference count of that page? No. It would need to do so if struct pages were ordinary kmalloc'ed objects; but they are more stable than that, and reused in particular ways according to particular rules. Access to stable_node from its pointer in struct page is no problem, so long as we never free a stable_node before the ksm page itself has been freed. Access to struct page from its pointer in stable_node: reintroduce get_ksm_page(), and let that peep out through its keyhole (the stable_node pointer to ksm page), to see if that struct page still holds the right key to open it (the ksm page mapping pointer back to this stable_node). This relies upon the established way in which free_hot_cold_page() sets an anon (including ksm) page->mapping to NULL; and relies upon no other user of a struct page to put something which looks like the original stable_node pointer (with two low bits also set) into page->mapping. It also needs get_page_unless_zero() technique pioneered by speculative pagecache; and uses rcu_read_lock() to keep the guarantees that gives. There are several drivers which put pointers of their own into page-> mapping; but none of those could coincide with our stable_node pointers, since KSM won't free a stable_node until it sees that the page has gone. The only problem case found is the pagetable spinlock USE_SPLIT_PTLOCKS places in struct page (my own abuse): to accommodate GENERIC_LOCKBREAK's break_lock on 32-bit, that spans both page->private and page->mapping. Since break_lock is only 0 or 1, again no confusion for get_ksm_page(). But what of DEBUG_SPINLOCK on 64-bit bigendian? When owner_cpu is 3 (matching PageKsm low bits), it might see 0xdead4ead00000003 in page-> mapping, which might coincide? We could get around that by... but a better answer is to suppress USE_SPLIT_PTLOCKS when DEBUG_SPINLOCK or DEBUG_LOCK_ALLOC, to stop bloating sizeof(struct page) in their case - already proposed in an earlier mm/Kconfig patch. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
For full functionality, page_referenced_one() and try_to_unmap_one() need to know the vma: to pass vma down to arch-dependent flushes, or to observe VM_LOCKED or VM_EXEC. But KSM keeps no record of vma: nor can it, since vmas get split and merged without its knowledge. Instead, note page's anon_vma in its rmap_item when adding to stable tree: all the vmas which might map that page are listed by its anon_vma. page_referenced_ksm() and try_to_unmap_ksm() then traverse the anon_vma, first to find the probable vma, that which matches rmap_item's mm; but if that is not enough to locate all instances, traverse again to try the others. This catches those occasions when fork has duplicated a pte of a ksm page, but ksmd has not yet come around to assign it an rmap_item. But each rmap_item in the stable tree which refers to an anon_vma needs to take a reference to it. Andrea's anon_vma design cleverly avoided a reference count (an anon_vma was free when its list of vmas was empty), but KSM now needs to add that. Is a 32-bit count sufficient? I believe so - the anon_vma is only free when both count is 0 and list is empty. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
Initial implementation for swapping out KSM's shared pages: add page_referenced_ksm() and try_to_unmap_ksm(), which rmap.c calls when faced with a PageKsm page. Most of what's needed can be got from the rmap_items listed from the stable_node of the ksm page, without discovering the actual vma: so in this patch just fake up a struct vma for page_referenced_one() or try_to_unmap_one(), then refine that in the next patch. Add VM_NONLINEAR to ksm_madvise()'s list of exclusions: it has always been implicit there (being only set with VM_SHARED, already excluded), but let's make it explicit, to help justify the lack of nonlinear unmap. Rely on the page lock to protect against concurrent modifications to that page's node of the stable tree. The awkward part is not swapout but swapin: do_swap_page() and page_add_anon_rmap() now have to allow for new possibilities - perhaps a ksm page still in swapcache, perhaps a swapcache page associated with one location in one anon_vma now needed for another location or anon_vma. (And the vma might even be no longer VM_MERGEABLE when that happens.) ksm_might_need_to_copy() checks for that case, and supplies a duplicate page when necessary, simply leaving it to a subsequent pass of ksmd to rediscover the identity and merge them back into one ksm page. Disappointingly primitive: but the alternative would have to accumulate unswappable info about the swapped out ksm pages, limiting swappability. Remove page_add_ksm_rmap(): page_add_anon_rmap() now has to allow for the particular case it was handling, so just use it instead. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
When KSM merges an mlocked page, it has been forgetting to munlock it: that's been left to free_page_mlock(), which reports it in /proc/vmstat as unevictable_pgs_mlockfreed instead of unevictable_pgs_munlocked (and whinges "Page flag mlocked set for process" in mmotm, whereas mainline is silently forgiving). Call munlock_vma_page() to fix that. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wright <chrisw@redhat.com> Acked-by: NRik van Riel <riel@redhat.com> Acked-by: NMel Gorman <mel@csn.ul.ie> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
Add a pointer to the ksm page into struct stable_node, holding a reference to the page while the node exists. Put a pointer to the stable_node into the ksm page's ->mapping. Then we don't need get_ksm_page() while traversing the stable tree: the page to compare against is sure to be present and correct, even if it's no longer visible through any of its existing rmap_items. And we can handle the forked ksm page case more efficiently: no need to memcmp our way through the tree to find its match. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
Though we still do well to keep rmap_items in the unstable tree without a separate tree_item at the node, for several reasons it becomes awkward to keep rmap_items in the stable tree without a separate stable_node: lack of space in the nicely-sized rmap_item, the need for an anchor as rmap_items are removed, the need for a node even when temporarily no rmap_items are attached to it. So declare struct stable_node (rb_node to place it in the tree and hlist_head for the rmap_items hanging off it), and convert stable tree handling to use it: without yet taking advantage of it. Note how one stable_tree_insert() of a node now has _two_ stable_tree_append()s of the two rmap_items being merged. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
Free up a pointer in struct rmap_item, by making the mm_slot's rmap_list a singly-linked list: we always traverse that list sequentially, and we don't even lose any prefetches (but should consider adding a few later). Name it rmap_list throughout. Do we need to free up that pointer? Not immediately, and in the end, we could continue to avoid it with a union; but having done the conversion, let's keep it this way, since there's no downside, and maybe we'll want more in future (struct rmap_item is a cache-friendly 32 bytes on 32-bit and 64 bytes on 64-bit, so we shall want to avoid expanding it). Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-
由 Hugh Dickins 提交于
Cleanup: make argument names more consistent from cmp_and_merge_page() down to replace_page(), so that it's easier to follow the rmap_item's page and the matching tree_page and the merged kpage through that code. In some places, e.g. break_cow(), pass rmap_item instead of separate mm and address. cmp_and_merge_page() initialize tree_page to NULL, to avoid a "may be used uninitialized" warning seen in one config by Anil SB. Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
-