From: Luis Chamberlain <mcgrof@kernel.org>
To: axboe@kernel.dk, viro@zeniv.linux.org.uk, bvanassche@acm.org,
gregkh@linuxfoundation.org, rostedt@goodmis.org,
mingo@redhat.com, jack@suse.cz, ming.lei@redhat.com,
nstange@suse.de, akpm@linux-foundation.org
Cc: mhocko@suse.com, yukuai3@huawei.com, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Luis Chamberlain <mcgrof@kernel.org>,
Omar Sandoval <osandov@fb.com>, Hannes Reinecke <hare@suse.com>,
Michal Hocko <mhocko@kernel.org>
Subject: [PATCH 4/5] mm/swapfile: refcount block and queue before using blkcg_schedule_throttle()
Date: Tue, 14 Apr 2020 04:19:01 +0000 [thread overview]
Message-ID: <20200414041902.16769-5-mcgrof@kernel.org> (raw)
In-Reply-To: <20200414041902.16769-1-mcgrof@kernel.org>
block devices are refcounted so to ensure once its final user goes away it
can be cleaned up by the lower layers properly. The block device's
request_queue structure is also refcounted, however, if the last
blk_put_queue() is called under atomic context the block layer has
to defer removal.
By refcounting the block device during the use of blkcg_schedule_throttle(),
we ensure ensure two things:
1) the block device remains available during the call
2) we ensure avoid having to deal with the fact we're using the
request_queue structure in atomic context, since the last
blk_put_queue() will be called upon disk_release(), *after*
our own bdput().
This means this code path is *not* going to remove the request_queue
structure, as we are ensuring some later upper layer disk_release()
will be the one to release the request_queue structure for us.
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: yu kuai <yukuai3@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
mm/swapfile.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6659ab563448..9285ff6030ca 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3753,6 +3753,7 @@ static void free_swap_count_continuations(struct swap_info_struct *si)
void mem_cgroup_throttle_swaprate(struct mem_cgroup *memcg, int node,
gfp_t gfp_mask)
{
+ struct block_device *bdev;
struct swap_info_struct *si, *next;
if (!(gfp_mask & __GFP_IO) || !memcg)
return;
@@ -3771,8 +3772,17 @@ void mem_cgroup_throttle_swaprate(struct mem_cgroup *memcg, int node,
plist_for_each_entry_safe(si, next, &swap_avail_heads[node],
avail_lists[node]) {
if (si->bdev) {
- blkcg_schedule_throttle(bdev_get_queue(si->bdev),
- true);
+ bdev = bdgrab(si->bdev);
+ if (!bdev)
+ continue;
+ /*
+ * By adding our own bdgrab() we ensure the queue
+ * sticks around until disk_release(), and so we ensure
+ * our release of the request_queue does not happen in
+ * atomic context.
+ */
+ blkcg_schedule_throttle(bdev_get_queue(bdev), true);
+ bdput(bdev);
break;
}
}
--
2.25.1
next prev parent reply other threads:[~2020-04-14 4:19 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 4:18 [PATCH 0/5] blktrace: fix use after free Luis Chamberlain
2020-04-14 4:18 ` [PATCH 1/5] block: move main block debugfs initialization to its own file Luis Chamberlain
2020-04-14 7:35 ` Greg KH
2020-04-15 2:44 ` Bart Van Assche
2020-04-14 4:18 ` [PATCH 2/5] blktrace: fix debugfs use after free Luis Chamberlain
2020-04-14 7:37 ` Greg KH
2020-04-14 15:38 ` Christoph Hellwig
2020-04-15 2:46 ` Bart Van Assche
2020-04-15 17:38 ` Eric Sandeen
2020-04-15 21:48 ` Bart Van Assche
2020-04-16 0:56 ` Luis Chamberlain
2020-04-16 1:02 ` Eric Sandeen
2020-04-16 1:20 ` Luis Chamberlain
2020-04-16 2:10 ` Ming Lei
2020-04-16 5:25 ` Luis Chamberlain
2020-04-16 5:47 ` Ming Lei
2020-04-16 6:09 ` Ming Lei
2020-04-16 6:22 ` Luis Chamberlain
2020-04-16 6:20 ` Luis Chamberlain
2020-04-16 6:28 ` Ming Lei
2020-04-17 4:09 ` Luis Chamberlain
2020-04-14 4:19 ` [PATCH 3/5] blktrace: refcount the request_queue during ioctl Luis Chamberlain
2020-04-14 15:40 ` Christoph Hellwig
2020-04-15 6:16 ` Luis Chamberlain
2020-04-15 7:14 ` Christoph Hellwig
2020-04-15 12:34 ` Luis Chamberlain
2020-04-15 12:39 ` Christoph Hellwig
2020-04-15 13:25 ` Luis Chamberlain
2020-04-15 14:18 ` Bart Van Assche
2020-04-16 1:12 ` Luis Chamberlain
2020-04-16 3:43 ` Bart Van Assche
2020-04-16 5:29 ` Luis Chamberlain
2020-04-15 14:45 ` Bart Van Assche
2020-04-16 1:17 ` Luis Chamberlain
2020-04-16 2:31 ` Ming Lei
2020-04-16 5:36 ` Luis Chamberlain
2020-04-14 4:19 ` Luis Chamberlain [this message]
2020-04-14 15:44 ` [PATCH 4/5] mm/swapfile: refcount block and queue before using blkcg_schedule_throttle() Christoph Hellwig
2020-04-15 5:42 ` Luis Chamberlain
2020-04-15 7:27 ` Christoph Hellwig
2020-04-15 7:34 ` Christoph Hellwig
2020-04-15 13:19 ` Luis Chamberlain
2020-04-16 6:10 ` Christoph Hellwig
2020-04-16 6:22 ` Ming Lei
2020-04-16 6:25 ` Luis Chamberlain
2020-04-16 6:34 ` Ming Lei
2020-04-14 4:19 ` [PATCH 5/5] block: revert back to synchronous request_queue removal Luis Chamberlain
2020-04-14 15:47 ` Christoph Hellwig
2020-04-14 20:58 ` Luis Chamberlain
2020-04-15 6:46 ` Christoph Hellwig
2020-04-15 13:20 ` Luis Chamberlain
2020-04-16 2:36 ` Ming Lei
2020-04-14 7:38 ` [PATCH 0/5] blktrace: fix use after free Greg KH
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=20200414041902.16769-5-mcgrof@kernel.org \
--to=mcgrof@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=bvanassche@acm.org \
--cc=gregkh@linuxfoundation.org \
--cc=hare@suse.com \
--cc=jack@suse.cz \
--cc=linux-block@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=mhocko@suse.com \
--cc=ming.lei@redhat.com \
--cc=mingo@redhat.com \
--cc=nstange@suse.de \
--cc=osandov@fb.com \
--cc=rostedt@goodmis.org \
--cc=viro@zeniv.linux.org.uk \
--cc=yukuai3@huawei.com \
/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).