c68ed79457
Disable preemption on -RT for the vmstat code. On vanila the code runs in IRQ-off regions while on -RT it may not when stats are updated under a local_lock. "preempt_disable" ensures that the same resources is not updated in parallel due to preemption. This patch differs from the preempt-rt version where __count_vm_event and __count_vm_events are also protected. The counters are explicitly "allowed to be to be racy" so there is no need to protect them from preemption. Only the accurate page stats that are updated by a read-modify-write need protection. This patch also differs in that a preempt_[en|dis]able_rt helper is not used. As vmstat is the only user of the helper, it was suggested that it be open-coded in vmstat.c instead of risking the helper being used in unnecessary contexts. Link: https://lkml.kernel.org/r/20210805160019.1137-2-mgorman@techsingularity.net Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.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.