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>
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Родитель
9e16b7fb1d
Коммит
56f31801cc
18
mm/memory.c
18
mm/memory.c
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@ -2954,7 +2954,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
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unsigned int flags, pte_t orig_pte)
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{
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spinlock_t *ptl;
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struct page *page, *swapcache = NULL;
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struct page *page, *swapcache;
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swp_entry_t entry;
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pte_t pte;
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int locked;
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@ -3005,9 +3005,11 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
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*/
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ret = VM_FAULT_HWPOISON;
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delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
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swapcache = page;
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goto out_release;
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}
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swapcache = page;
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locked = lock_page_or_retry(page, mm, flags);
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delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
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@ -3025,16 +3027,12 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
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if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
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goto out_page;
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swapcache = page;
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page = ksm_might_need_to_copy(page, vma, address);
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if (unlikely(!page)) {
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ret = VM_FAULT_OOM;
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page = swapcache;
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swapcache = NULL;
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goto out_page;
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}
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if (page == swapcache)
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swapcache = NULL;
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if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
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ret = VM_FAULT_OOM;
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@ -3078,10 +3076,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
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}
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flush_icache_page(vma, page);
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set_pte_at(mm, address, page_table, pte);
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if (swapcache) /* ksm created a completely new copy */
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page_add_new_anon_rmap(page, vma, address);
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else
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if (page == swapcache)
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do_page_add_anon_rmap(page, vma, address, exclusive);
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else /* ksm created a completely new copy */
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page_add_new_anon_rmap(page, vma, address);
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/* It's better to call commit-charge after rmap is established */
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mem_cgroup_commit_charge_swapin(page, ptr);
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@ -3089,7 +3087,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
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if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
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try_to_free_swap(page);
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unlock_page(page);
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if (swapcache) {
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if (page != swapcache) {
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/*
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* Hold the lock to avoid the swap entry to be reused
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* until we take the PT lock for the pte_same() check
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@ -3122,7 +3120,7 @@ out_page:
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unlock_page(page);
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out_release:
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page_cache_release(page);
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if (swapcache) {
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if (page != swapcache) {
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unlock_page(swapcache);
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page_cache_release(swapcache);
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}
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