From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Mel Gorman <mgorman@suse.de>, Petr Holasek <pholasek@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Izik Eidus <izik.eidus@ravellosystems.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 6/7] mm: cleanup "swapcache" in do_swap_page
Date: Thu, 21 Feb 2013 00:27:39 -0800 (PST) [thread overview]
Message-ID: <alpine.LNX.2.00.1302210025480.17843@eggly.anvils> (raw)
In-Reply-To: <alpine.LNX.2.00.1302210013120.17843@eggly.anvils>
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>
---
mm/memory.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)
--- mmotm.orig/mm/memory.c 2013-02-20 22:43:47.228023344 -0800
+++ mmotm/mm/memory.c 2013-02-20 23:21:00.304076416 -0800
@@ -2954,7 +2954,7 @@ static int do_swap_page(struct mm_struct
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
*/
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
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
}
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
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);
}
--
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next prev parent reply other threads:[~2013-02-21 8:28 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-21 8:17 [PATCH 0/7] ksm: responses to NUMA review Hugh Dickins
2013-02-21 8:19 ` [PATCH 1/7] ksm: add some comments Hugh Dickins
2013-02-22 4:26 ` Ric Mason
2013-02-22 20:50 ` Hugh Dickins
2013-02-21 8:20 ` [PATCH 2/7] ksm: treat unstable nid like in stable tree Hugh Dickins
2013-02-22 7:13 ` Ric Mason
2013-02-22 21:03 ` Hugh Dickins
2013-03-01 5:29 ` Ric Mason
2013-03-01 20:03 ` Hugh Dickins
2013-03-02 1:10 ` Ric Mason
2013-03-02 2:57 ` Hugh Dickins
2013-03-06 1:28 ` Will Huck
2013-03-06 4:31 ` Hugh Dickins
2013-03-06 2:37 ` Ric Mason
2013-03-06 5:05 ` Hugh Dickins
2013-03-06 6:58 ` Ric Mason
2013-03-06 10:18 ` Ric Mason
2013-03-07 23:26 ` Ric Mason
2013-02-21 8:22 ` [PATCH 3/7] ksm: shrink 32-bit rmap_item back to 32 bytes Hugh Dickins
2013-02-21 8:23 ` [PATCH 4/7] mm,ksm: FOLL_MIGRATION do migration_entry_wait Hugh Dickins
2013-02-21 8:25 ` [PATCH 5/7] mm,ksm: swapoff might need to copy Hugh Dickins
2013-02-21 14:53 ` Johannes Weiner
2013-02-22 17:16 ` Hugh Dickins
2013-02-21 8:27 ` Hugh Dickins [this message]
2013-02-21 8:29 ` [PATCH 7/7] ksm: allocate roots when needed Hugh Dickins
2013-02-22 3:44 ` [PATCH 0/7] ksm: responses to NUMA review Ric Mason
2013-02-22 20:38 ` Hugh Dickins
2013-02-24 1:39 ` Ric Mason
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