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| author |   Hugh Dickins <hughd@google.com> | 2013-02-22 16:36:10 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-23 17:50:24 -0800 |
| commit | 56f31801ccdecb420d0d1fd2bf9f337c355214a9 (patch) | |
| tree | 868442b02e6c83bdd52e4e129b17b90341190b6d /mm/memory.c | |
| parent | mm,ksm: swapoff might need to copy (diff) | |
| download | linux-dev-56f31801ccdecb420d0d1fd2bf9f337c355214a9.tar.xz linux-dev-56f31801ccdecb420d0d1fd2bf9f337c355214a9.zip | |
mm: cleanup "swapcache" in do_swap_page
I dislike the way in which "swapcache" gets used in do_swap_page():
there is always a page from swapcache there (even if maybe uncached by
the time we lock it), but tests are made according to "swapcache".
Rework that with "page != swapcache", as has been done in unuse_pte().
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Petr Holasek <pholasek@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Izik Eidus <izik.eidus@ravellosystems.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>
Diffstat (limited to '')
| -rw-r--r-- | mm/memory.c | 18 |
1 files changed, 8 insertions, 10 deletions
diff --git a/mm/memory.c b/mm/memory.c index ec8ba011fa7d..705473afc1f4 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2954,7 +2954,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned int flags, pte_t orig_pte) { spinlock_t *ptl; - struct page *page, *swapcache = NULL; + struct page *page, *swapcache; swp_entry_t entry; pte_t pte; int locked; @@ -3005,9 +3005,11 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, */ ret = VM_FAULT_HWPOISON; delayacct_clear_flag(DELAYACCT_PF_SWAPIN); + swapcache = page; goto out_release; } + swapcache = page; locked = lock_page_or_retry(page, mm, flags); delayacct_clear_flag(DELAYACCT_PF_SWAPIN); @@ -3025,16 +3027,12 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) goto out_page; - swapcache = page; page = ksm_might_need_to_copy(page, vma, address); if (unlikely(!page)) { ret = VM_FAULT_OOM; page = swapcache; - swapcache = NULL; goto out_page; } - if (page == swapcache) - swapcache = NULL; if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { ret = VM_FAULT_OOM; @@ -3078,10 +3076,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, } flush_icache_page(vma, page); set_pte_at(mm, address, page_table, pte); - if (swapcache) /* ksm created a completely new copy */ - page_add_new_anon_rmap(page, vma, address); - else + if (page == swapcache) do_page_add_anon_rmap(page, vma, address, exclusive); + else /* ksm created a completely new copy */ + page_add_new_anon_rmap(page, vma, address); /* It's better to call commit-charge after rmap is established */ mem_cgroup_commit_charge_swapin(page, ptr); @@ -3089,7 +3087,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) try_to_free_swap(page); unlock_page(page); - if (swapcache) { + if (page != swapcache) { /* * Hold the lock to avoid the swap entry to be reused * until we take the PT lock for the pte_same() check @@ -3122,7 +3120,7 @@ out_page: unlock_page(page); out_release: page_cache_release(page); - if (swapcache) { + if (page != swapcache) { unlock_page(swapcache); page_cache_release(swapcache); } |