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Filename Latest commit message Latest commit date
Josef Bacik 3c821cc5ed btrfs: check page->mapping when loading free space cache
commit 3797136b626ad4b6582223660c041efdea8f26b2 upstream.

While testing 5.2 we ran into the following panic

[52238.017028] BUG: kernel NULL pointer dereference, address: 0000000000000001
[52238.105608] RIP: 0010:drop_buffers+0x3d/0x150
[52238.304051] Call Trace:
[52238.308958]  try_to_free_buffers+0x15b/0x1b0
[52238.317503]  shrink_page_list+0x1164/0x1780
[52238.325877]  shrink_inactive_list+0x18f/0x3b0
[52238.334596]  shrink_node_memcg+0x23e/0x7d0
[52238.342790]  ? do_shrink_slab+0x4f/0x290
[52238.350648]  shrink_node+0xce/0x4a0
[52238.357628]  balance_pgdat+0x2c7/0x510
[52238.365135]  kswapd+0x216/0x3e0
[52238.371425]  ? wait_woken+0x80/0x80
[52238.378412]  ? balance_pgdat+0x510/0x510
[52238.386265]  kthread+0x111/0x130
[52238.392727]  ? kthread_create_on_node+0x60/0x60
[52238.401782]  ret_from_fork+0x1f/0x30

The page we were trying to drop had a page->private, but had no
page->mapping and so called drop_buffers, assuming that we had a
buffer_head on the page, and then panic'ed trying to deref 1, which is
our page->private for data pages.

This is happening because we're truncating the free space cache while
we're trying to load the free space cache.  This isn't supposed to
happen, and I'll fix that in a followup patch.  However we still
shouldn't allow those sort of mistakes to result in messing with pages
that do not belong to us.  So add the page->mapping check to verify that
we still own this page after dropping and re-acquiring the page lock.

This page being unlocked as:
btrfs_readpage
  extent_read_full_page
    __extent_read_full_page
      __do_readpage
        if (!nr)
	   unlock_page  <-- nr can be 0 only if submit_extent_page
			    returns an error

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add callchain ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-17 19:56:02 +01:00
arch ARM: dts: pandora-common: define wl1251 as child node of mmc3 2019-12-17 19:55:39 +01:00
block iocost: check active_list of all the ancestors in iocg_activate() 2019-11-14 13:56:54 -07:00
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 iwlwifi: pcie: fix support for transmitting SKBs with fraglist 2019-12-17 19:56:01 +01:00
fs btrfs: check page->mapping when loading free space cache 2019-12-17 19:56:02 +01:00
include compat_ioctl: add compat_ptr_ioctl() 2019-12-17 19:55:30 +01:00
init
ipc
kernel time: Zero the upper 32-bits in __kernel_timespec on 32-bit 2019-12-13 08:42:18 +01:00
lib lib/xz: fix XZ_DYNALLOC to avoid useless memory reallocations 2019-11-15 18:34:00 -08:00
LICENSES
mm mm/ksm.c: don't WARN if page is still mapped in remove_stable_node() 2019-11-22 09:11:18 -08:00
net rfkill: allocate static minor 2019-12-13 08:43:18 +01:00
samples
scripts arm64 fix for -rc8 / final 2019-11-15 09:14:23 -08:00
security
sound ALSA: hda - Fix pending unsol events at shutdown 2019-12-13 08:43:27 +01:00
tools kselftest: Fix NULL INSTALL_PATH for TARGETS runlist 2019-12-13 08:43:31 +01:00
usr
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
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 5.4.3 2019-12-13 08:43:32 +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.