From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>,
Rik van Riel <riel@redhat.com>, Vlastimil Babka <vbabka@suse.cz>,
Christoph Lameter <cl@gentwo.org>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Steve Capper <steve.capper@linaro.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.cz>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH 15/19] futex, thp: remove special case for THP in get_futex_key
Date: Wed, 5 Nov 2014 16:49:50 +0200 [thread overview]
Message-ID: <1415198994-15252-16-git-send-email-kirill.shutemov@linux.intel.com> (raw)
In-Reply-To: <1415198994-15252-1-git-send-email-kirill.shutemov@linux.intel.com>
With new THP refcounting, we don't need tricks to stabilize huge page.
If we've got reference to tail page, it can't split under us.
This patch effectively reverts a5b338f2b0b1.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
kernel/futex.c | 61 ++++++++++++----------------------------------------------
1 file changed, 12 insertions(+), 49 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index d3a9d946d0b7..fb71ccba683b 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -391,7 +391,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
{
unsigned long address = (unsigned long)uaddr;
struct mm_struct *mm = current->mm;
- struct page *page, *page_head;
+ struct page *page;
int err, ro = 0;
/*
@@ -434,46 +434,9 @@ again:
else
err = 0;
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- page_head = page;
- if (unlikely(PageTail(page))) {
- put_page(page);
- /* serialize against __split_huge_page_splitting() */
- local_irq_disable();
- if (likely(__get_user_pages_fast(address, 1, !ro, &page) == 1)) {
- page_head = compound_head(page);
- /*
- * page_head is valid pointer but we must pin
- * it before taking the PG_lock and/or
- * PG_compound_lock. The moment we re-enable
- * irqs __split_huge_page_splitting() can
- * return and the head page can be freed from
- * under us. We can't take the PG_lock and/or
- * PG_compound_lock on a page that could be
- * freed from under us.
- */
- if (page != page_head) {
- get_page(page_head);
- put_page(page);
- }
- local_irq_enable();
- } else {
- local_irq_enable();
- goto again;
- }
- }
-#else
- page_head = compound_head(page);
- if (page != page_head) {
- get_page(page_head);
- put_page(page);
- }
-#endif
-
- lock_page(page_head);
-
+ lock_page(page);
/*
- * If page_head->mapping is NULL, then it cannot be a PageAnon
+ * If page->mapping is NULL, then it cannot be a PageAnon
* page; but it might be the ZERO_PAGE or in the gate area or
* in a special mapping (all cases which we are happy to fail);
* or it may have been a good file page when get_user_pages_fast
@@ -485,12 +448,12 @@ again:
*
* The case we do have to guard against is when memory pressure made
* shmem_writepage move it from filecache to swapcache beneath us:
- * an unlikely race, but we do need to retry for page_head->mapping.
+ * an unlikely race, but we do need to retry for page->mapping.
*/
- if (!page_head->mapping) {
- int shmem_swizzled = PageSwapCache(page_head);
- unlock_page(page_head);
- put_page(page_head);
+ if (!page->mapping) {
+ int shmem_swizzled = PageSwapCache(page);
+ unlock_page(page);
+ put_page(page);
if (shmem_swizzled)
goto again;
return -EFAULT;
@@ -503,7 +466,7 @@ again:
* it's a read-only handle, it's expected that futexes attach to
* the object not the particular process.
*/
- if (PageAnon(page_head)) {
+ if (PageAnon(page)) {
/*
* A RO anonymous page will never change and thus doesn't make
* sense for futex operations.
@@ -518,15 +481,15 @@ again:
key->private.address = address;
} else {
key->both.offset |= FUT_OFF_INODE; /* inode-based key */
- key->shared.inode = page_head->mapping->host;
+ key->shared.inode = page->mapping->host;
key->shared.pgoff = basepage_index(page);
}
get_futex_key_refs(key); /* implies MB (B) */
out:
- unlock_page(page_head);
- put_page(page_head);
+ unlock_page(page);
+ put_page(page);
return err;
}
--
2.1.1
next prev parent reply other threads:[~2014-11-05 14:50 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-05 14:49 [PATCHv2 RFC 00/19] THP refcounting redesign Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 01/19] mm, thp: drop FOLL_SPLIT Kirill A. Shutemov
2014-11-25 3:01 ` Naoya Horiguchi
2014-11-25 14:04 ` Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 02/19] thp: cluster split_huge_page* code together Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 03/19] mm: change PageAnon() to work on tail pages Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 04/19] mm: avoid PG_locked " Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 05/19] rmap: add argument to charge compound page Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 06/19] mm: store mapcount for compound page separate Kirill A. Shutemov
2014-11-18 8:43 ` Naoya Horiguchi
2014-11-18 9:58 ` Kirill A. Shutemov
2014-11-18 23:41 ` Naoya Horiguchi
2014-11-19 0:54 ` Kirill A. Shutemov
2014-11-21 6:41 ` Aneesh Kumar K.V
2014-11-21 11:47 ` Kirill A. Shutemov
2014-11-19 10:51 ` Jerome Marchand
2014-11-19 13:00 ` Kirill A. Shutemov
2014-11-19 13:15 ` Jerome Marchand
2014-11-20 20:06 ` Christoph Lameter
2014-11-21 12:01 ` Kirill A. Shutemov
2014-11-21 6:12 ` Aneesh Kumar K.V
2014-11-21 12:02 ` Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 07/19] mm, thp: adjust conditions when we can reuse the page on WP fault Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 08/19] mm: prepare migration code for new THP refcounting Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 09/19] thp: rename split_huge_page_pmd() to split_huge_pmd() Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 10/19] thp: PMD splitting without splitting compound page Kirill A. Shutemov
2014-11-19 6:57 ` Naoya Horiguchi
2014-11-19 13:02 ` Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 11/19] mm, vmstats: new THP splitting event Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 12/19] thp: implement new split_huge_page() Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 13/19] mm, thp: remove infrastructure for handling splitting PMDs Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 14/19] x86, thp: remove " Kirill A. Shutemov
2014-11-05 14:49 ` Kirill A. Shutemov [this message]
2014-11-05 14:49 ` [PATCH 16/19] thp: update documentation Kirill A. Shutemov
2014-11-19 8:07 ` Naoya Horiguchi
2014-11-19 13:11 ` Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 17/19] mlock, thp: HACK: split all pages in VM_LOCKED vma Kirill A. Shutemov
2014-11-19 9:02 ` Naoya Horiguchi
2014-11-19 13:08 ` Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 18/19] tho, mm: use migration entries to freeze page counts on split Kirill A. Shutemov
2014-11-05 14:49 ` [PATCH 19/19] mm, thp: remove compound_lock Kirill A. Shutemov
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