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authorHugh Dickins <hughd@google.com>2013-02-22 16:36:10 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-23 17:50:24 -0800
commit56f31801ccdecb420d0d1fd2bf9f337c355214a9 (patch)
tree868442b02e6c83bdd52e4e129b17b90341190b6d /mm/memory.c
parent9e16b7fb1d066d38d01fd57c449f2640c5d208cb (diff)
downloadlinux-56f31801ccdecb420d0d1fd2bf9f337c355214a9.tar.gz
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 'mm/memory.c')
-rw-r--r--mm/memory.c18
1 files changed, 8 insertions, 10 deletions
diff --git a/mm/memory.c b/mm/memory.c
index ec8ba011fa7..705473afc1f 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);
}