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Cedric Xing 4040b84ec0 x86: make page fault handling disable interrupts properly 
[ Upstream commit 614da1d3d4 ]

There's a big comment in the x86 do_page_fault() about our interrupt
disabling code:

    * User address page fault handling might have reenabled
    * interrupts. Fixing up all potential exit points of
    * do_user_addr_fault() and its leaf functions is just not
    * doable w/o creating an unholy mess or turning the code
    * upside down.

but it turns out that comment is subtly wrong, and the code as a result
is also wrong.

Because it's certainly true that we may have re-enabled interrupts when
handling user page faults.  And it's most certainly true that we don't
want to bother fixing up all the cases.

But what isn't true is that it's limited to user address page faults.

The confusion stems from the fact that we have logic here that depends
on the address range of the access, but other code then depends on the
_context_ the access was done in.  The two are not related, even though
both of them are about user-vs-kernel.

In other words, both user and kernel addresses can cause interrupts to
have been enabled (eg when __bad_area_nosemaphore() gets called for user
accesses to kernel addresses).  As a result we should make sure to
disable interrupts again regardless of the address range before
returning to the low-level fault handling code.

The __bad_area_nosemaphore() code actually did disable interrupts again
after enabling them, just not consistently.  Ironically, as noted in the
original comment, fixing up all the cases is just not worth it, when the
simple solution is to just do it unconditionally in one single place.

So remove the incomplete case that unsuccessfully tried to do what the
comment said was "not doable" in commit ca4c6a9858 ("x86/traps: Make
interrupt enable/disable symmetric in C code"), and just make it do the
simple and straightforward thing.

Signed-off-by: Cedric Xing <cedric.xing@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Fixes: ca4c6a9858 ("x86/traps: Make interrupt enable/disable symmetric in C code")
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-01-30 10:32:22 +01:00
arch x86: make page fault handling disable interrupts properly 2026-01-30 10:32:22 +01:00
block block: zero non-PI portion of auto integrity buffer 2026-01-23 11:21:16 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: authencesn - reject too-short AAD (assoclen<8) to match ESP/ESN spec 2026-01-30 10:32:12 +01:00
Documentation fou: Don't allow 0 for FOU_ATTR_IPPROTO. 2026-01-30 10:32:12 +01:00
drivers Octeontx2-af: Add proper checks for fwdata 2026-01-30 10:32:22 +01:00
fs fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() 2026-01-30 10:32:15 +01:00
include mm/hugetlb: fix hugetlb_pmd_shared() 2026-01-30 10:32:15 +01:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/io-wq: check IO_WQ_BIT_EXIT inside work run loop 2026-01-30 10:32:15 +01:00
ipc namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
kernel sched/fair: Fix pelt clock sync when entering idle 2026-01-30 10:32:20 +01:00
lib lib/buildid: use __kernel_read() for sleepable context 2026-01-23 11:21:25 +01:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm: restore per-memcg proactive reclaim with !CONFIG_NUMA 2026-01-30 10:32:15 +01:00
net net/sched: act_ife: avoid possible NULL deref 2026-01-30 10:32:21 +01:00
rust rust: bitops: fix missing _find_* functions on 32-bit ARM 2026-01-23 11:21:12 +01:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2026-01-08 10:17:11 +01:00
scripts kconfig: fix static linking of nconf 2026-01-30 10:32:16 +01:00
security landlock: Fix wrong type usage 2026-01-23 11:21:22 +01:00
sound ALSA: usb: Increase volume range that triggers a warning 2026-01-30 10:32:17 +01:00
tools vsock/test: fix seqpacket message bounds test 2026-01-30 10:32:21 +01:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM: Fix last_boosted_vcpu index assignment bug 2026-01-02 12:57:21 +01:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap 8 hotfixes. 4 are cc:stable, 7 are against mm/. 2025-11-26 12:38:05 -08:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS soc: fixes for 6.18, part 4 2025-11-28 09:57:31 -08:00
Makefile Linux 6.18.7 2026-01-23 11:21:37 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.