From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
To: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: [PATCH] mm/filemap: do not allocate cache pages beyond end of file at read
Date: Mon, 28 Oct 2019 12:59:34 +0300 [thread overview]
Message-ID: <157225677483.3442.4227193290486305330.stgit@buzz> (raw)
Page cache could contain pages beyond end of file during write or
if read races with truncate. But generic_file_buffered_read() always
allocates unneeded pages beyond eof if somebody reads here and one
extra page at the end if file size is page-aligned.
Function generic_file_buffered_read() calls page_cache_sync_readahead()
if page not found in cache and then do another lookup. Readahead checks
file size in __do_page_cache_readahead() before allocating pages.
After that generic_file_buffered_read() falls back to slow path and
allocates page for ->readpage() without checking file size.
This patch checks file size before allocating page for ->readpage().
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
mm/filemap.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/filemap.c b/mm/filemap.c
index 85b7d087eb45..92abf5f348a9 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2225,6 +2225,10 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
goto out;
no_cached_page:
+ /* Do not allocate cache pages beyond end of file. */
+ if (((loff_t)index << PAGE_SHIFT) >= i_size_read(inode))
+ goto out;
+
/*
* Ok, it wasn't cached, so we need to create a new
* page..
next reply other threads:[~2019-10-28 9:59 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-28 9:59 Konstantin Khlebnikov [this message]
2019-10-28 12:39 ` [PATCH] mm/filemap: do not allocate cache pages beyond end of file at read Linus Torvalds
2019-10-28 12:42 ` Kirill A. Shutemov
2019-10-28 12:47 ` Linus Torvalds
2019-10-28 12:57 ` Kirill A. Shutemov
2019-10-29 14:25 ` Konstantin Khlebnikov
2019-10-29 16:52 ` Linus Torvalds
2019-10-30 6:50 ` Kirill A. Shutemov
2019-10-30 7:02 ` Linus Torvalds
2019-10-30 10:34 ` Steven Whitehouse
2019-10-30 10:54 ` Linus Torvalds
2019-10-31 11:40 ` Steven Whitehouse
2019-11-22 23:59 ` Andreas Grünbacher
2019-11-25 10:52 ` Steven Whitehouse
2019-11-25 17:05 ` Linus Torvalds
2019-11-27 15:41 ` Steven Whitehouse
2019-11-27 16:29 ` Andreas Gruenbacher
2019-11-27 17:29 ` Linus Torvalds
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=157225677483.3442.4227193290486305330.stgit@buzz \
--to=khlebnikov@yandex-team.ru \
--cc=akpm@linux-foundation.org \
--cc=hannes@cmpxchg.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).