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Chris Wilson e80e88ef60 drm/i915/userptr: Try to acquire the page lock around set_page_dirty() 
commit 2d691aeca4 upstream.

set_page_dirty says:

	For pages with a mapping this should be done under the page lock
	for the benefit of asynchronous memory errors who prefer a
	consistent dirty state. This rule can be broken in some special
	cases, but should be better not to.

Under those rules, it is only safe for us to use the plain set_page_dirty
calls for shmemfs/anonymous memory. Userptr may be used with real
mappings and so needs to use the locked version (set_page_dirty_lock).

However, following a try_to_unmap() we may want to remove the userptr and
so call put_pages(). However, try_to_unmap() acquires the page lock and
so we must avoid recursively locking the pages ourselves -- which means
that we cannot safely acquire the lock around set_page_dirty(). Since we
can't be sure of the lock, we have to risk skip dirtying the page, or
else risk calling set_page_dirty() without a lock and so risk fs
corruption.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203317
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112012
Fixes: 5cc9ed4b9a ("drm/i915: Introduce mapping of user pages into video memory (userptr) ioctl")
References: cb6d7c7dc7 ("drm/i915/userptr: Acquire the page lock around set_page_dirty()")
References: 505a8ec7e1 ("Revert "drm/i915/userptr: Acquire the page lock around set_page_dirty()"")
References: 6dcc693bc5 ("ext4: warn when page is dirtied without buffers")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191111133205.11590-1-chris@chris-wilson.co.uk
(cherry picked from commit 0d4bbe3d40)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
(cherry picked from commit cee7fb437e)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-01 09:16:12 +01:00
arch x86/resctrl: Fix rdt_find_domain() return value and checks 2019-11-24 08:21:09 +01:00
block blok, bfq: do not plug I/O if all queues are weight-raised 2019-11-20 18:46:44 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: fix a memory leak in rsa-kcs1pad's encryption mode 2019-11-20 18:47:44 +01:00
Documentation net: phy: mdio-bcm-unimac: Allow configuring MDIO clock divider 2019-11-20 18:47:14 +01:00
drivers drm/i915/userptr: Try to acquire the page lock around set_page_dirty() 2019-12-01 09:16:12 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Revert "fs: ocfs2: fix possible null-pointer dereferences in ocfs2_xa_prepare_entry()" 2019-12-01 09:16:10 +01:00
include cpuidle: menu: Fix wakeup statistics updates for polling state 2019-11-24 08:20:07 +01:00
init initramfs: don't free a non-existent initrd 2019-10-01 08:26:09 +02:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel bpf: btf: Fix a missing check bug 2019-11-24 08:20:53 +01:00
lib idr: Fix idr_get_next race with idr_remove 2019-11-24 08:19:11 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/ksm.c: don't WARN if page is still mapped in remove_stable_node() 2019-12-01 09:16:11 +01:00
net vhost/vsock: split packets to send using multiple buffers 2019-12-01 09:16:08 +01:00
samples mei: samples: fix a signedness bug in amt_host_if_call() 2019-11-24 08:19:50 +01:00
scripts scripts/setlocalversion: Improve -dirty check with git-status --no-optional-locks 2019-11-06 13:05:27 +01:00
security ima: fix freeing ongoing ahash_request 2019-10-11 18:21:11 +02:00
sound ALSA: hda/ca0132 - Fix input effect controls for desktop cards 2019-11-24 08:20:49 +01:00
tools tools: gpio: Correctly add make dependencies for gpio_utils 2019-12-01 09:16:09 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:57:16 +02:00
virt kvm: arm/arm64: Fix stage2_flush_memslot for 4 level page table 2019-11-24 08:19:31 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.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 Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.86 2019-11-24 08:21:09 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

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.
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.