70df07838f
Do not increase the node count unless a node has been successfully read,
because it can lead to a segfault if an error occurs.
For example, if perf exceeds the open file limit in memory_node__read(),
which, on a test system, could be made to happen by setting the file limit
to exactly 32:
Before:
$ ulimit -n 32
$ perf mem record --all-user -- sleep 1
[ perf record: Woken up 1 times to write data ]
failed: can't open memory sysfs data
perf: Segmentation fault
Obtained 14 stack frames.
perf(sighandler_dump_stack+0x48) [0x55f4b1f59558]
/lib/x86_64-linux-gnu/libc.so.6(+0x42520) [0x7f4ba1c42520]
/lib/x86_64-linux-gnu/libc.so.6(free+0x1e) [0x7f4ba1ca53fe]
perf(+0x178ff4) [0x55f4b1f48ff4]
perf(+0x179a70) [0x55f4b1f49a70]
perf(+0x17ef5d) [0x55f4b1f4ef5d]
perf(+0x85c0b) [0x55f4b1e55c0b]
perf(cmd_record+0xe1d) [0x55f4b1e5920d]
perf(cmd_mem+0xc96) [0x55f4b1e80e56]
perf(+0x130460) [0x55f4b1f00460]
perf(main+0x689) [0x55f4b1e427d9]
/lib/x86_64-linux-gnu/libc.so.6(+0x29d90) [0x7f4ba1c29d90]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x80) [0x7f4ba1c29e40]
perf(_start+0x25) [0x55f4b1e42a25]
Segmentation fault (core dumped)
$
After:
$ ulimit -n 32
$ perf mem record --all-user -- sleep 1
[ perf record: Woken up 1 times to write data ]
failed: can't open memory sysfs data
[ perf record: Captured and wrote 0.005 MB perf.data (11 samples) ]
$
Fixes: f8e502b9d1b3b197 ("perf header: Ensure bitmaps are freed")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20231123075848.9652-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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.