Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Matthew Wilcox <willy@infradead.org>,
	linux-mm@kvack.org
Subject: [PATCH 06/10] mm/khugepaged: collapse_shmem() remember to clear holes
Date: Mon, 26 Nov 2018 15:26:34 -0800 (PST)
Message-ID: <alpine.LSU.2.11.1811261525080.2275@eggly.anvils> (raw)
In-Reply-To: <alpine.LSU.2.11.1811261444420.2275@eggly.anvils>

Huge tmpfs testing reminds us that there is no __GFP_ZERO in the gfp
flags khugepaged uses to allocate a huge page - in all common cases it
would just be a waste of effort - so collapse_shmem() must remember to
clear out any holes that it instantiates.

The obvious place to do so, where they are put into the page cache tree,
is not a good choice: because interrupts are disabled there.  Leave it
until further down, once success is assured, where the other pages are
copied (before setting PageUptodate).

Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: stable@vger.kernel.org # 4.8+
---
 mm/khugepaged.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 65e82f665c7c..1c402d33547e 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1467,7 +1467,12 @@ static void collapse_shmem(struct mm_struct *mm,
 		 * Replacing old pages with new one has succeeded, now we
 		 * need to copy the content and free the old pages.
 		 */
+		index = start;
 		list_for_each_entry_safe(page, tmp, &pagelist, lru) {
+			while (index < page->index) {
+				clear_highpage(new_page + (index % HPAGE_PMD_NR));
+				index++;
+			}
 			copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
 					page);
 			list_del(&page->lru);
@@ -1477,6 +1482,11 @@ static void collapse_shmem(struct mm_struct *mm,
 			ClearPageActive(page);
 			ClearPageUnevictable(page);
 			put_page(page);
+			index++;
+		}
+		while (index < end) {
+			clear_highpage(new_page + (index % HPAGE_PMD_NR));
+			index++;
 		}
 
 		local_irq_disable();
-- 
2.20.0.rc0.387.gc7a69e6b6c-goog

  parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-26 23:13 [PATCH 00/10] huge_memory,khugepaged tmpfs split/collapse fixes Hugh Dickins
2018-11-26 23:19 ` [PATCH 02/10] mm/huge_memory: splitting set mapping+index before unfreeze Hugh Dickins
2018-11-27  7:26   ` Kirill A. Shutemov
2018-11-26 23:21 ` [PATCH 03/10] mm/huge_memory: fix lockdep complaint on 32-bit i_size_read() Hugh Dickins
2018-11-27  7:27   ` Kirill A. Shutemov
2018-11-26 23:23 ` [PATCH 04/10] mm/khugepaged: collapse_shmem() stop if punched or truncated Hugh Dickins
2018-11-27  7:31   ` Kirill A. Shutemov
2018-11-27 13:26   ` Matthew Wilcox
2018-11-26 23:25 ` [PATCH 05/10] mm/khugepaged: fix crashes due to misaccounted holes Hugh Dickins
2018-11-27  7:35   ` Kirill A. Shutemov
2018-11-26 23:26 ` Hugh Dickins [this message]
2018-11-27  7:38   ` [PATCH 06/10] mm/khugepaged: collapse_shmem() remember to clear holes Kirill A. Shutemov
2018-11-26 23:27 ` [PATCH 07/10] mm/khugepaged: minor reorderings in collapse_shmem() Hugh Dickins
2018-11-27  7:59   ` Kirill A. Shutemov
2018-11-27 20:23     ` Hugh Dickins
2018-11-28 10:59       ` Kirill A. Shutemov
2018-11-28 19:40         ` Hugh Dickins
2018-11-26 23:29 ` [PATCH 08/10] mm/khugepaged: collapse_shmem() without freezing new_page Hugh Dickins
2018-11-27  8:01   ` Kirill A. Shutemov
2018-11-26 23:31 ` [PATCH 09/10] mm/khugepaged: collapse_shmem() do not crash on Compound Hugh Dickins
2018-11-26 23:33 ` [PATCH 10/10] mm/khugepaged: fix the xas_create_range() error path Hugh Dickins
2018-11-27  8:02   ` Kirill A. Shutemov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=alpine.LSU.2.11.1811261525080.2275@eggly.anvils \
    --to=hughd@google.com \
    --cc=akpm@linux-foundation.org \
    --cc=kirill.shutemov@linux.intel.com \
    --cc=kirill@shutemov.name \
    --cc=linux-mm@kvack.org \
    --cc=willy@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git