9a543f007b
After the memory is freed, it can be immediately allocated by other
CPUs, before the "free" trace report has been emitted. This causes
inaccurate traces.
For example, if the following sequence of events occurs:
CPU 0 CPU 1
(1) alloc xxxxxx
(2) free xxxxxx
(3) alloc xxxxxx
(4) free xxxxxx
Then they will be inaccurately reported via tracing, so that they appear
to have happened in this order:
CPU 0 CPU 1
(1) alloc xxxxxx
(2) alloc xxxxxx
(3) free xxxxxx
(4) free xxxxxx
This makes it look like CPU 1 somehow managed to allocate memory that
CPU 0 still had allocated for itself.
In order to avoid this, emit the "free xxxxxx" tracing report just
before the actual call to free the memory, instead of just after it.
Link: https://lkml.kernel.org/r/374eb75d-7404-8721-4e1e-65b0e5b17279@huawei.com
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
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.