From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>, Jan Kara <jack@suse.cz>,
Matthew Wilcox <willy@infradead.org>,
Josef Bacik <josef@toxicpanda.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Minchan Kim <minchan@kernel.org>, Robert Stupp <snazy@gmx.de>
Subject: [PATCH 1/3] mm: Don't bother dropping mmap_sem for zero size readahead
Date: Wed, 12 Feb 2020 14:16:12 -0800 [thread overview]
Message-ID: <20200212221614.215302-1-minchan@kernel.org> (raw)
From: Jan Kara <jack@suse.cz>
When handling a page fault, we drop mmap_sem to start async readahead so
that we don't block on IO submission with mmap_sem held. However
there's no point to drop mmap_sem in case readahead is disabled. Handle
that case to avoid pointless dropping of mmap_sem and retrying the
fault. This was actually reported to block mlockall(MCL_CURRENT)
indefinitely.
Fixes: 6b4c9f446981 ("filemap: drop the mmap_sem for all blocking operations")
Reported-by: Minchan Kim <minchan@kernel.org>
Reported-by: Robert Stupp <snazy@gmx.de>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
mm/filemap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 1784478270e1..5bffaa2176cd 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2416,7 +2416,7 @@ static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
pgoff_t offset = vmf->pgoff;
/* If we don't want any read-ahead, don't bother */
- if (vmf->vma->vm_flags & VM_RAND_READ)
+ if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages)
return fpin;
if (ra->mmap_miss > 0)
ra->mmap_miss--;
--
2.25.0.225.g125e21ebc7-goog
next reply other threads:[~2020-02-12 22:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 22:16 Minchan Kim [this message]
2020-02-12 22:16 ` [PATCH 2/3] mm: fix long time stall from mm_populate Minchan Kim
2020-04-21 4:12 ` Andrew Morton
2020-02-12 22:16 ` [PATCH 3/3] mm: make PageReadahead more strict Minchan Kim
2020-02-17 9:31 ` Jan Kara
2020-02-18 22:28 ` Minchan Kim
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=20200212221614.215302-1-minchan@kernel.org \
--to=minchan@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=hannes@cmpxchg.org \
--cc=jack@suse.cz \
--cc=josef@toxicpanda.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=snazy@gmx.de \
--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
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).