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Filename Latest commit message Latest commit date
Josef Bacik e3fb5bb7eb btrfs: do not call synchronize_srcu() in inode_tree_del
commit f72ff01df9cf5db25c76674cac16605992d15467 upstream.

Testing with the new fsstress uncovered a pretty nasty deadlock with
lookup and snapshot deletion.

Process A
unlink
 -> final iput
   -> inode_tree_del
     -> synchronize_srcu(subvol_srcu)

Process B
btrfs_lookup  <- srcu_read_lock() acquired here
  -> btrfs_iget
    -> find inode that has I_FREEING set
      -> __wait_on_freeing_inode()

We're holding the srcu_read_lock() while doing the iget in order to make
sure our fs root doesn't go away, and then we are waiting for the inode
to finish freeing.  However because the free'ing process is doing a
synchronize_srcu() we deadlock.

Fix this by dropping the synchronize_srcu() in inode_tree_del().  We
don't need people to stop accessing the fs root at this point, we're
only adding our empty root to the dead roots list.

A larger much more invasive fix is forthcoming to address how we deal
with fs roots, but this fixes the immediate problem.

Fixes: 76dda93c6a ("Btrfs: add snapshot/subvolume destroy ioctl")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-31 16:41:53 +01:00
arch ARM: tegra: Fix FLOW_CTLR_HALT register clobbering by tegra_resume() 2019-12-21 11:04:48 +01:00
block block: fix "check bi_size overflow before merge" 2019-12-21 11:04:32 +01:00
certs
crypto crypto: user - fix memory leak in crypto_reportstat 2019-12-13 08:43:11 +01:00
Documentation USB: documentation: flags on usb-storage versus UAS 2019-12-17 19:55:32 +01:00
drivers NFC: nxp-nci: Fix probing without ACPI 2019-12-31 16:41:49 +01:00
fs btrfs: do not call synchronize_srcu() in inode_tree_del 2019-12-31 16:41:53 +01:00
include neighbour: remove neigh_cleanup() method 2019-12-31 16:41:37 +01:00
init
ipc
kernel workqueue: Fix missing kfree(rescuer) in destroy_workqueue() 2019-12-17 19:56:54 +01:00
lib lib: raid6: fix awk build warnings 2019-12-17 19:56:09 +01:00
LICENSES
mm mm/shmem.c: cast the type of unmap_start to u64 2019-12-17 19:56:51 +01:00
net neighbour: remove neigh_cleanup() method 2019-12-31 16:41:37 +01:00
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: hda: Fix regression by strip mask fix 2019-12-21 11:05:23 +01:00
tools selftests: forwarding: Delete IPv6 address at the end 2019-12-31 16:41:36 +01:00
usr kbuild: update compile-test header list for v5.4-rc2 2019-10-05 15:29:49 +09:00
virt KVM: arm/arm64: vgic: Don't rely on the wrong pending table 2019-12-13 08:43:00 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-22 14:28:14 -08:00
Makefile Linux 5.4.6 2019-12-21 11:05:23 +01:00
README

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.