From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [merged] loop-limit-the-number-of-requests-in-the-bio-list.patch removed from -mm tree Date: Mon, 03 Dec 2012 14:01:50 -0800 Message-ID: <20121203220150.CE553100047@wpzn3.hot.corp.google.com> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail-gg0-f202.google.com ([209.85.161.202]:59477 "EHLO mail-gg0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751008Ab2LCWBw (ORCPT ); Mon, 3 Dec 2012 17:01:52 -0500 Received: by mail-gg0-f202.google.com with SMTP id k1so407010ggn.1 for ; Mon, 03 Dec 2012 14:01:51 -0800 (PST) Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: lczerner@redhat.com, a.p.zijlstra@chello.nl, axboe@kernel.dk, david@fromorbit.com, dhowells@redhat.com, jmoyer@redhat.com, mingo@elte.hu, neilb@suse.de, mm-commits@vger.kernel.org The patch titled Subject: loop: limit the number of requests in the bio list has been removed from the -mm tree. Its filename was loop-limit-the-number-of-requests-in-the-bio-list.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Lukas Czerner Subject: loop: limit the number of requests in the bio list Currently there is no limit on the number of requests in the loop bio list. This can lead into some nasty situations when the caller spawns tons of bio requests taking huge amount of memory. This is even more obvious with discard where blkdev_issue_discard() will submit all bios for the range and wait for them to finish afterwards. On really big loop devices and slow backing file system this can lead to OOM situation as reported by Dave Chinner. With this patch we will wait in loop_make_request() if the number of bios in the loop bio list would exceed 'nr_congestion_on'. We'll wake up the process as we process the bios form the list. Some threshold hysteresis is in place to avoid high frequency oscillation. Signed-off-by: Lukas Czerner Reported-by: Dave Chinner Cc: Neil Brown Cc: David Howells Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Jens Axboe Acked-by: Jeff Moyer Signed-off-by: Andrew Morton --- drivers/block/loop.c | 10 ++++++++++ include/linux/loop.h | 3 +++ 2 files changed, 13 insertions(+) diff -puN drivers/block/loop.c~loop-limit-the-number-of-requests-in-the-bio-list drivers/block/loop.c --- a/drivers/block/loop.c~loop-limit-the-number-of-requests-in-the-bio-list +++ a/drivers/block/loop.c @@ -463,6 +463,7 @@ out: */ static void loop_add_bio(struct loop_device *lo, struct bio *bio) { + lo->lo_bio_count++; bio_list_add(&lo->lo_bio_list, bio); } @@ -471,6 +472,7 @@ static void loop_add_bio(struct loop_dev */ static struct bio *loop_get_bio(struct loop_device *lo) { + lo->lo_bio_count--; return bio_list_pop(&lo->lo_bio_list); } @@ -489,6 +491,10 @@ static void loop_make_request(struct req goto out; if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY))) goto out; + if (lo->lo_bio_count >= q->nr_congestion_on) + wait_event_lock_irq(lo->lo_req_wait, + lo->lo_bio_count < q->nr_congestion_off, + lo->lo_lock); loop_add_bio(lo, old_bio); wake_up(&lo->lo_event); spin_unlock_irq(&lo->lo_lock); @@ -546,6 +552,8 @@ static int loop_thread(void *data) continue; spin_lock_irq(&lo->lo_lock); bio = loop_get_bio(lo); + if (lo->lo_bio_count < lo->lo_queue->nr_congestion_off) + wake_up(&lo->lo_req_wait); spin_unlock_irq(&lo->lo_lock); BUG_ON(!bio); @@ -873,6 +881,7 @@ static int loop_set_fd(struct loop_devic lo->transfer = transfer_none; lo->ioctl = NULL; lo->lo_sizelimit = 0; + lo->lo_bio_count = 0; lo->old_gfp_mask = mapping_gfp_mask(mapping); mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); @@ -1673,6 +1682,7 @@ static int loop_add(struct loop_device * lo->lo_number = i; lo->lo_thread = NULL; init_waitqueue_head(&lo->lo_event); + init_waitqueue_head(&lo->lo_req_wait); spin_lock_init(&lo->lo_lock); disk->major = LOOP_MAJOR; disk->first_minor = i << part_shift; diff -puN include/linux/loop.h~loop-limit-the-number-of-requests-in-the-bio-list include/linux/loop.h --- a/include/linux/loop.h~loop-limit-the-number-of-requests-in-the-bio-list +++ a/include/linux/loop.h @@ -53,10 +53,13 @@ struct loop_device { spinlock_t lo_lock; struct bio_list lo_bio_list; + unsigned int lo_bio_count; int lo_state; struct mutex lo_ctl_mutex; struct task_struct *lo_thread; wait_queue_head_t lo_event; + /* wait queue for incoming requests */ + wait_queue_head_t lo_req_wait; struct request_queue *lo_queue; struct gendisk *lo_disk; _ Patches currently in -mm which might be from lczerner@redhat.com are linux-next.patch