linux-next

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Filipe Manana b1517622f2 Btrfs: fix deadlock between dedup on same file and starting writeback If we are deduping two ranges of the same file we need to make sure that we lock all pages in ascending order, that is, lock first the pages from the range with lower offset and then the pages from the other range, as otherwise we can deadlock with a concurrent task that is starting delalloc (writeback). Example trace: [74073.052218] INFO: task kworker/u32:10:17997 blocked for more than 120 seconds. [74073.053889] Tainted: G W 4.9.0-rc7-btrfs-next-36+ #1 [74073.055071] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [74073.056696] kworker/u32:10 D 0 17997 2 0x00000000 [74073.058606] Workqueue: writeback wb_workfn (flush-btrfs-53176) [74073.061370] ffff880031e79858 ffff8802159d2580 ffff880237004580 ffff880031e79240 [74073.064784] ffff88023f4978c0 ffffc9000817b638 ffffffff814c15e1 0000000000000000 [74073.068386] ffff88023f4978d8 ffff88023f4978c0 000000000017b620 ffff880031e79240 [74073.071712] Call Trace: [74073.072884] [<ffffffff814c15e1>] ? __schedule+0x48f/0x6f4 [74073.075395] [<ffffffff814c1c8b>] ? bit_wait+0x2f/0x2f [74073.077511] [<ffffffff814c18d2>] schedule+0x8c/0xa0 [74073.079440] [<ffffffff814c4b36>] schedule_timeout+0x43/0xff [74073.081637] [<ffffffff8110953e>] ? time_hardirqs_on+0x9/0x14 [74073.083809] [<ffffffff81095c67>] ? trace_hardirqs_on_caller+0x16/0x197 [74073.086314] [<ffffffff810bde98>] ? timekeeping_get_ns+0x1e/0x32 [74073.100654] [<ffffffff810be048>] ? ktime_get+0x41/0x52 [74073.102619] [<ffffffff814c10f0>] io_schedule_timeout+0xa0/0x102 [74073.104771] [<ffffffff814c10f0>] ? io_schedule_timeout+0xa0/0x102 [74073.106969] [<ffffffff814c1ca6>] bit_wait_io+0x1b/0x39 [74073.108954] [<ffffffff814c1fb8>] __wait_on_bit_lock+0x4f/0x99 [74073.110981] [<ffffffff8112b692>] __lock_page+0x6b/0x6d [74073.112833] [<ffffffff8108ceb4>] ? autoremove_wake_function+0x3a/0x3a [74073.115010] [<ffffffffa031178b>] lock_page+0x2f/0x32 [btrfs] [74073.116999] [<ffffffffa0311d9f>] lock_delalloc_pages+0xc7/0x1a0 [btrfs] [74073.119243] [<ffffffffa0313d15>] find_lock_delalloc_range+0xc3/0x1a4 [btrfs] [74073.121636] [<ffffffffa0313e81>] writepage_delalloc.isra.31+0x8b/0x134 [btrfs] [74073.124229] [<ffffffffa0315d69>] __extent_writepage+0x1c1/0x2bf [btrfs] [74073.126372] [<ffffffffa03160f2>] extent_write_cache_pages.isra.30.constprop.49+0x28b/0x36c [btrfs] [74073.129371] [<ffffffffa03165b9>] extent_writepages+0x4b/0x5c [btrfs] [74073.131440] [<ffffffffa02fcb59>] ? insert_reserved_file_extent.constprop.42+0x261/0x261 [btrfs] [74073.134303] [<ffffffff811b4ce4>] ? writeback_sb_inodes+0xe0/0x4a1 [74073.136298] [<ffffffffa02fab7f>] btrfs_writepages+0x28/0x2a [btrfs] [74073.138248] [<ffffffff81138200>] do_writepages+0x23/0x2c [74073.139910] [<ffffffff811b3cab>] __writeback_single_inode+0x105/0x6d2 [74073.142003] [<ffffffff811b4e96>] writeback_sb_inodes+0x292/0x4a1 [74073.136298] [<ffffffffa02fab7f>] btrfs_writepages+0x28/0x2a [btrfs] [74073.138248] [<ffffffff81138200>] do_writepages+0x23/0x2c [74073.139910] [<ffffffff811b3cab>] __writeback_single_inode+0x105/0x6d2 [74073.142003] [<ffffffff811b4e96>] writeback_sb_inodes+0x292/0x4a1 [74073.143911] [<ffffffff811b511b>] __writeback_inodes_wb+0x76/0xae [74073.145787] [<ffffffff811b53ca>] wb_writeback+0x1cc/0x4d7 [74073.147452] [<ffffffff811b60cd>] wb_workfn+0x194/0x37d [74073.149084] [<ffffffff811b60cd>] ? wb_workfn+0x194/0x37d [74073.150726] [<ffffffff8106ce77>] ? process_one_work+0x154/0x4e4 [74073.152694] [<ffffffff8106cf96>] process_one_work+0x273/0x4e4 [74073.154452] [<ffffffff8106d6db>] worker_thread+0x1eb/0x2ca [74073.156138] [<ffffffff8106d4f0>] ? rescuer_thread+0x2b6/0x2b6 [74073.157837] [<ffffffff81072a81>] kthread+0xd5/0xdd [74073.159339] [<ffffffff810729ac>] ? __kthread_unpark+0x5a/0x5a [74073.161088] [<ffffffff814c6257>] ret_from_fork+0x27/0x40 [74073.162680] INFO: lockdep is turned off. [74073.163855] INFO: task do-dedup:30264 blocked for more than 120 seconds. [74073.181180] Tainted: G W 4.9.0-rc7-btrfs-next-36+ #1 [74073.181180] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [74073.185296] fdm-stress D 0 30264 29974 0x00000000 [74073.186810] ffff880089595118 ffff880211b8eac0 ffff880237030380 ffff880089594b00 [74073.188998] ffff88023f2978c0 ffffc900063abb68 ffffffff814c15e1 0000000000000000 [74073.191070] ffff88023f2978d8 ffff88023f2978c0 00000000003abb50 ffff880089594b00 [74073.193286] Call Trace: [74073.193990] [<ffffffff814c15e1>] ? __schedule+0x48f/0x6f4 [74073.195418] [<ffffffff814c1c8b>] ? bit_wait+0x2f/0x2f [74073.196796] [<ffffffff814c18d2>] schedule+0x8c/0xa0 [74073.198163] [<ffffffff814c4b36>] schedule_timeout+0x43/0xff [74073.199621] [<ffffffff81095df5>] ? trace_hardirqs_on+0xd/0xf [74073.201100] [<ffffffff810bde98>] ? timekeeping_get_ns+0x1e/0x32 [74073.202686] [<ffffffff810be048>] ? ktime_get+0x41/0x52 [74073.204051] [<ffffffff814c10f0>] io_schedule_timeout+0xa0/0x102 [74073.205585] [<ffffffff814c10f0>] ? io_schedule_timeout+0xa0/0x102 [74073.207123] [<ffffffff814c1ca6>] bit_wait_io+0x1b/0x39 [74073.208238] [<ffffffff814c1fb8>] __wait_on_bit_lock+0x4f/0x99 [74073.208871] [<ffffffff8112b692>] __lock_page+0x6b/0x6d [74073.209430] [<ffffffff8108ceb4>] ? autoremove_wake_function+0x3a/0x3a [74073.210101] [<ffffffff8112b800>] lock_page+0x2f/0x32 [74073.210636] [<ffffffff8112c502>] pagecache_get_page+0x5e/0x153 [74073.211270] [<ffffffffa03257eb>] gather_extent_pages+0x4e/0x109 [btrfs] [74073.212166] [<ffffffffa032a04c>] btrfs_dedupe_file_range+0x1e1/0x4dd [btrfs] [74073.213257] [<ffffffff8118d9b5>] vfs_dedupe_file_range+0x1c1/0x221 [74073.214086] [<ffffffff8119e0c4>] do_vfs_ioctl+0x442/0x600 [74073.214767] [<ffffffff811a7874>] ? rcu_read_unlock+0x5b/0x5d [74073.215619] [<ffffffff811a7953>] ? __fget+0x6b/0x77 [74073.216338] [<ffffffff8119e2d9>] SyS_ioctl+0x57/0x79 [74073.217149] [<ffffffff814c5fea>] entry_SYSCALL_64_fastpath+0x18/0xad [74073.218102] [<ffffffff81109552>] ? time_hardirqs_off+0x9/0x14 [74073.218968] [<ffffffff810938ce>] ? trace_hardirqs_off_caller+0x1f/0xaa [74073.219938] INFO: lockdep is turned off. What happened was the following: CPU 1 CPU 2 btrfs_dedupe_file_range() --> using same inode as source and target --> src range is [768K, 1Mb[ --> dst range is [0, 256K[ btrfs_cmp_data_prepare() --> calls gather_extent_pages() for range [768K, 1Mb[ and locks all pages in that range do_writepages() btrfs_writepages() extent_writepages() extent_write_cache_pages() __extent_writepage() writepage_delalloc() find_lock_delalloc_range() --> finds range [0, 1Mb[ lock_delalloc_pages() --> locks all pages in the range [0, 768K[ --> tries to lock page at offset 768K --> deadlock --> calls gather_extent_pages() to lock pages in the range [0, 256K[ --> deadlock, task at CPU 1 already locked that range and it's trying to lock the range we locked previously So fix this by making sure that during a dedup we always lock first the pages from the range with lower offset. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>		2017-02-22 15:55:02 -08:00
arch	Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-02-11 10:31:46 -08:00
block	block: don't try Write Same from __blkdev_issue_zeroout	2017-02-06 09:34:46 -07:00
certs	certs: Add a secondary system keyring that can be added to dynamically	2016-04-11 22:48:09 +01:00
crypto	crypto: algif_aead - Fix kernel panic on list_del	2017-02-03 17:45:48 +08:00
Documentation	media fixes for v4.10-rc8	2017-02-06 14:37:55 -08:00
drivers	Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-02-11 10:14:24 -08:00
firmware	WHENCE: use https://linuxtv.org for LinuxTV URLs	2015-12-04 10:35:11 -02:00
fs	Btrfs: fix deadlock between dedup on same file and starting writeback	2017-02-22 15:55:02 -08:00
include	btrfs: Make btrfs_ino take a struct btrfs_inode	2017-02-14 15:50:51 +01:00
init	kbuild: modversions: add infrastructure for emitting relative CRCs	2017-02-03 08:28:25 -08:00
ipc	ipc/sem.c: fix incorrect sem_lock pairing	2017-01-10 18:31:55 -08:00
kernel	Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-02-11 10:24:16 -08:00
lib	mm: do not export ioremap_page_range symbol for external module	2017-01-24 16:26:14 -08:00
mm	mm/slub.c: fix random_seq offset destruction	2017-02-08 15:41:43 -08:00
net	l2tp: do not use udp_ioctl()	2017-02-10 15:57:34 -05:00
samples	bpf: fix samples xdp_tx_iptunnel and tc_l2_redirect with fake KBUILD_MODNAME	2017-01-20 12:04:07 -05:00
scripts	kbuild: modversions: add infrastructure for emitting relative CRCs	2017-02-03 08:28:25 -08:00
security	selinux: fix off-by-one in setprocattr	2017-02-08 19:09:53 +11:00
sound	ALSA: hda - adding a new NV HDMI/DP codec ID in the driver	2017-02-09 08:57:47 +01:00
tools	perf/urgent fixes:	2017-02-03 20:42:30 +01:00
usr	kbuild: initramfs cleanup, set target from Kconfig	2017-01-05 09:40:16 -08:00
virt	KVM/ARM updates for 4.10-rc4	2017-01-17 15:04:59 +01:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes	.gitattributes: set git diff driver for C source code files	2016-10-07 18:46:30 -07:00
.gitignore	Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild	2016-08-02 16:48:52 -04:00
.mailmap	mailmap: add codeaurora.org names for nameless email commits	2017-01-10 18:31:55 -08:00
COPYING
CREDITS	CREDITS: Remove outdated address information	2016-12-21 15:21:29 -08:00
Kbuild	scripts/gdb: provide linux constants	2016-05-23 17:04:14 -07:00
Kconfig
MAINTAINERS	ARM: SoC fixes for v4.10	2017-02-08 10:01:39 -08:00
Makefile	Linux 4.10-rc8	2017-02-12 13:03:20 -08:00
README	README: add a new README file, pointing to the Documentation/	2016-10-24 08:12:35 -02:00

README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.