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Nadav Amit 8f1d56f64f x86/mm/tlb: Ignore f->new_tlb_gen when zero
Commit aa44284960 ("x86/mm/tlb: Avoid reading mm_tlb_gen when
possible") introduced an optimization to skip superfluous TLB
flushes based on the generation provided in flush_tlb_info.

However, arch_tlbbatch_flush() does not provide any generation in
flush_tlb_info and populates the flush_tlb_info generation with
0.  This 0 is causes the flush_tlb_info to be interpreted as a
superfluous, old flush.  As a result, try_to_unmap_one() would
not perform any TLB flushes.

Fix it by checking whether f->new_tlb_gen is nonzero. Zero value
is anyhow is an invalid generation value. To avoid future
confusion, introduce TLB_GENERATION_INVALID constant and use it
properly. Add warnings to ensure no partial flushes are done with
TLB_GENERATION_INVALID or when f->mm is NULL, since this does not
make any sense.

In addition, add the missing unlikely().

[ dhansen: change VM_BUG_ON() -> VM_WARN_ON(), clarify changelog ]

Fixes: aa44284960 ("x86/mm/tlb: Avoid reading mm_tlb_gen when possible")
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Hugh Dickins <hughd@google.com>
Link: https://lkml.kernel.org/r/20220710232837.3618-1-namit@vmware.com
2022-07-19 09:04:52 -07:00
arch x86/mm/tlb: Ignore f->new_tlb_gen when zero 2022-07-19 09:04:52 -07:00
block for-5.19/drivers-2022-05-22 2022-05-23 14:04:14 -07:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation Documentation/protection-keys: Clean up documentation for User Space pkeys 2022-06-07 16:06:22 -07:00
drivers Perf events changes for this cycle were: 2022-05-24 10:59:38 -07:00
fs arm64 updates for 5.19: 2022-05-23 21:06:11 -07:00
include Scheduler changes in this cycle were: 2022-05-24 11:11:13 -07:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel Scheduler changes in this cycle were: 2022-05-24 11:11:13 -07:00
lib Objtool changes for this cycle were: 2022-05-24 10:36:38 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm arm64 updates for 5.19: 2022-05-23 21:06:11 -07:00
net for-5.19/io_uring-net-2022-05-22 2022-05-23 12:51:04 -07:00
samples sched/tracing: Append prev_state to tp args instead 2022-05-12 00:37:11 +02:00
scripts Objtool changes for this cycle were: 2022-05-24 10:36:38 -07:00
security selinux: fix bad cleanup on error in hashtab_duplicate() 2022-05-17 18:34:35 -04:00
sound xen: branch for v5.19-rc1 2022-05-23 20:49:45 -07:00
tools Perf events changes for this cycle were: 2022-05-24 10:59:38 -07:00
usr Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
virt KVM: Free new dirty bitmap if creating a new memslot fails 2022-05-20 13:02:05 -04:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap Scheduler changes in this cycle were: 2022-05-24 11:11:13 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Scheduler changes in this cycle were: 2022-05-24 11:11:13 -07:00
Makefile Objtool changes for this cycle were: 2022-05-24 10:36:38 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.