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[ Upstream commit 6db2526c1d694c91c6e05e2f186c085e9460f202 ] Setting and clearing CPU bits in the mm_cpumask is only ever done by the CPU itself, from the context switch code or the TLB flush code. Synchronization is handled by switch_mm_irqs_off() blocking interrupts. Sending TLB flush IPIs to CPUs that are in the mm_cpumask, but no longer running the program causes a regression in the will-it-scale tlbflush2 test. This test is contrived, but a large regression here might cause a small regression in some real world workload. Instead of always sending IPIs to CPUs that are in the mm_cpumask, but no longer running the program, send these IPIs only once a second. The rest of the time we can skip over CPUs where the loaded_mm is different from the target mm. Reported-by: kernel test roboto <oliver.sang@intel.com> Signed-off-by: Rik van Riel <riel@surriel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20241204210316.612ee573@fangorn Closes: https://lore.kernel.org/oe-lkp/202411282207.6bd28eae-lkp@intel.com/ Signed-off-by: Sasha Levin <sashal@kernel.org>
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.