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Uladzislau Rezki (Sony)
0272d07ef6
Switch from the atomic_long_add_return() to its relaxed version.
We do not need a full memory barrier or any memory ordering during
increasing the "vmap_lazy_nr" variable. What we only need is to do it
atomically. This is what atomic_long_add_return_relaxed() guarantees.
AARCH64:
<snip>
Default:
40ec: d34cfe94 lsr x20, x20, #12
40f0: 14000044 b 4200 <free_vmap_area_noflush+0x19c>
40f4: 94000000 bl 0 <__sanitizer_cov_trace_pc>
40f8: 90000000 adrp x0, 0 <__traceiter_alloc_vmap_area>
40fc: 91000000 add x0, x0, #0x0
4100: f8f40016 ldaddal x20, x22, [x0]
4104: 8b160296 add x22, x20, x22
Relaxed:
40ec: d34cfe94 lsr x20, x20, #12
40f0: 14000044 b 4200 <free_vmap_area_noflush+0x19c>
40f4: 94000000 bl 0 <__sanitizer_cov_trace_pc>
40f8: 90000000 adrp x0, 0 <__traceiter_alloc_vmap_area>
40fc: 91000000 add x0, x0, #0x0
4100: f8340016 ldadd x20, x22, [x0]
4104: 8b160296 add x22, x20, x22
<snip>
Link: https://lkml.kernel.org/r/20250415112646.113091-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christop Hellwig <hch@infradead.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@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 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.