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Ville Syrjälä cb4daf2713 drm: Don't unref the same fb many times by mistake due to deadlock handling
If we get a deadlock after the fb lookup in drm_mode_page_flip_ioctl()
we proceed to unref the fb and then retry the whole thing from the top.
But we forget to reset the fb pointer back to NULL, and so if we then
get another error during the retry, before the fb lookup, we proceed
the unref the same fb again without having gotten another reference.
The end result is that the fb will (eventually) end up being freed
while it's still in use.

Reset fb to NULL once we've unreffed it to avoid doing it again
until we've done another fb lookup.

This turned out to be pretty easy to hit on a DG2 when doing async
flips (and CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y). The first symptom I
saw that drm_closefb() simply got stuck in a busy loop while walking
the framebuffer list. Fortunately I was able to convince it to oops
instead, and from there it was easier to track down the culprit.

Cc: stable@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231211081625.25704-1-ville.syrjala@linux.intel.com
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
2023-12-23 07:31:05 +02:00
arch parisc architecture fixes for kernel v6.7-rc3: 2023-11-26 09:59:39 -08:00
block vfs-6.7-rc3.fixes 2023-11-24 09:45:40 -08:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression in ahash and hides the Kconfig sub-options for the jitter RNG. 2023-11-09 17:04:58 -08:00
Documentation drm/doc: ci: Add IGT version details for flaky tests 2023-12-13 15:18:30 -03:00
drivers drm: Don't unref the same fb many times by mistake due to deadlock handling 2023-12-23 07:31:05 +02:00
fs eventfs fixes: 2023-11-26 19:48:20 -08:00
include drm: using mul_u32_u32() requires linux/math64.h 2023-12-19 15:29:17 +02:00
init As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
io_uring io_uring: fix off-by one bvec index 2023-11-20 15:21:38 -07:00
ipc Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
kernel Fix lockdep block chain corruption resulting in KASAN warnings. 2023-11-26 08:30:11 -08:00
lib parisc architecture fixes for kernel v6.7-rc3: 2023-11-26 09:59:39 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm vfs-6.7-rc3.fixes 2023-11-24 09:45:40 -08:00
net tls: fix NULL deref on tls_sw_splice_eof() with empty record 2023-11-23 08:51:45 -08:00
rust Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
samples Landlock updates for v6.7-rc1 2023-11-03 09:28:53 -10:00
scripts scripts/checkstack.pl: match all stack sizes for s390 2023-11-22 15:06:23 +01:00
security + Features 2023-11-03 09:48:17 -10:00
sound drm-misc-next for 6.8: 2023-11-20 09:50:09 +01:00
tools parisc architecture fixes for kernel v6.7-rc3: 2023-11-26 09:59:39 -08:00
usr arch: Remove Itanium (IA-64) architecture 2023-09-11 08:13:17 +00:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: generate kernel.spec in rpmbuild/SPECS/ 2023-10-03 20:49:09 +09:00
.mailmap As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
.rustfmt.toml
COPYING
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS MAINTAINERS: Add myself as a reviewer for rockchip drm 2023-12-13 15:37:31 +01:00
Makefile Linux 6.7-rc3 2023-11-26 19:59:33 -08:00
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.