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Dennis Zhou 46bcff2bfc btrfs: fix compressed write bio blkcg attribution
Bio attribution is handled at bio_set_dev() as once we have a device, we
have a corresponding request_queue and then can derive the current css.
In special cases, we want to attribute to bio to someone else. This can
be done by calling bio_associate_blkg_from_css() or
kthread_associate_blkcg() depending on the scenario. Btrfs does this for
compressed writeback as they are handled by kworkers, so the latter can
be done here.

Commit 1a41802701 ("btrfs: drop bio_set_dev where not needed") removes
early bio_set_dev() calls prior to submit_stripe_bio(). This breaks the
above assumption that we'll have a request_queue when we are doing
association. To fix this, switch to using kthread_associate_blkcg().

Without this, we crash in btrfs/024:

  [ 3052.093088] BUG: kernel NULL pointer dereference, address: 0000000000000510
  [ 3052.107013] #PF: supervisor read access in kernel mode
  [ 3052.107014] #PF: error_code(0x0000) - not-present page
  [ 3052.107015] PGD 0 P4D 0
  [ 3052.107021] Oops: 0000 [#1] SMP
  [ 3052.138904] CPU: 42 PID: 201270 Comm: kworker/u161:0 Kdump: loaded Not tainted 5.5.0-rc1-00062-g4852d8ac90a9 #712
  [ 3052.138905] Hardware name: Quanta Tioga Pass Single Side 01-0032211004/Tioga Pass Single Side, BIOS F08_3A18 12/20/2018
  [ 3052.138912] Workqueue: btrfs-delalloc btrfs_work_helper
  [ 3052.191375] RIP: 0010:bio_associate_blkg_from_css+0x1e/0x3c0
  [ 3052.191379] RSP: 0018:ffffc900210cfc90 EFLAGS: 00010282
  [ 3052.191380] RAX: 0000000000000000 RBX: ffff88bfe5573c00 RCX: 0000000000000000
  [ 3052.191382] RDX: ffff889db48ec2f0 RSI: ffff88bfe5573c00 RDI: ffff889db48ec2f0
  [ 3052.191386] RBP: 0000000000000800 R08: 0000000000203bb0 R09: ffff889db16b2400
  [ 3052.293364] R10: 0000000000000000 R11: ffff88a07fffde80 R12: ffff889db48ec2f0
  [ 3052.293365] R13: 0000000000001000 R14: ffff889de82bc000 R15: ffff889e2b7bdcc8
  [ 3052.293367] FS:  0000000000000000(0000) GS:ffff889ffba00000(0000) knlGS:0000000000000000
  [ 3052.293368] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 3052.293369] CR2: 0000000000000510 CR3: 0000000002611001 CR4: 00000000007606e0
  [ 3052.293370] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  [ 3052.293371] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  [ 3052.293372] PKRU: 55555554
  [ 3052.293376] Call Trace:
  [ 3052.402552]  btrfs_submit_compressed_write+0x137/0x390
  [ 3052.402558]  submit_compressed_extents+0x40f/0x4c0
  [ 3052.422401]  btrfs_work_helper+0x246/0x5a0
  [ 3052.422408]  process_one_work+0x200/0x570
  [ 3052.438601]  ? process_one_work+0x180/0x570
  [ 3052.438605]  worker_thread+0x4c/0x3e0
  [ 3052.438614]  kthread+0x103/0x140
  [ 3052.460735]  ? process_one_work+0x570/0x570
  [ 3052.460737]  ? kthread_mod_delayed_work+0xc0/0xc0
  [ 3052.460744]  ret_from_fork+0x24/0x30

Fixes: 1a41802701 ("btrfs: drop bio_set_dev where not needed")
Reported-by: Chris Murphy <chris@colorremedies.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-12-30 16:07:19 +01:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-16 16:10:59 -08:00
block iocost: check active_list of all the ancestors in iocg_activate() 2019-11-14 13:56:54 -07:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
Documentation Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-12 10:53:24 -08:00
drivers Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2019-11-17 08:15:41 -08:00
fs btrfs: fix compressed write bio blkcg attribution 2019-12-30 16:07:19 +01:00
include btrfs: rename btrfs_block_group_cache 2019-11-18 17:51:51 +01:00
init Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
ipc ipc/sem.c: convert to use built-in RCU list checking 2019-09-25 17:51:41 -07:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-17 08:30:38 -08:00
lib lib/xz: fix XZ_DYNALLOC to avoid useless memory reallocations 2019-11-15 18:34:00 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/debug.c: PageAnon() is true for PageKsm() pages 2019-11-15 18:34:00 -08:00
net ipmr: Fix skb headroom in ipmr_get_route(). 2019-11-16 13:06:54 -08:00
samples samples/bpf: fix build by setting HAVE_ATTR_TEST to zero 2019-10-31 21:39:15 +01:00
scripts arm64 fix for -rc8 / final 2019-11-15 09:14:23 -08:00
security efi/efi_test: Lock down /dev/efi_test and require CAP_SYS_ADMIN 2019-10-31 09:40:21 +01:00
sound ALSA: usb-audio: Fix incorrect size check for processing/extension units 2019-11-14 18:01:22 +01:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-16 15:52:00 -08:00
usr kbuild: update compile-test header list for v5.4-rc2 2019-10-05 15:29:49 +09:00
virt KVM: Add a comment describing the /dev/kvm no_compat handling 2019-11-15 10:14:04 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS IOMMU Fixes for Linux v5.4-rc7 2019-11-17 11:27:44 -08:00
Makefile Linux 5.4-rc8 2019-11-17 14:47:30 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.