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commitce9f1c05d2upstream. When MMAP2 has the PERF_RECORD_MISC_MMAP_BUILD_ID flag, it means the record already has the build-id info. So it marks the DSO as hit, to skip if the same DSO is not processed if it happens to miss the build-id later. But it missed to copy the MMAP2 record itself so it'd fail to symbolize samples for those regions. For example, the following generates 249 MMAP2 events. $ perf record --buildid-mmap -o- true | perf report --stat -i- | grep MMAP2 MMAP2 events: 249 (86.8%) Adding perf inject should not change the number of events like this $ perf record --buildid-mmap -o- true | perf inject -b | \ > perf report --stat -i- | grep MMAP2 MMAP2 events: 249 (86.5%) But when --buildid-all is used, it eats most of the MMAP2 events. $ perf record --buildid-mmap -o- true | perf inject -b --buildid-all | \ > perf report --stat -i- | grep MMAP2 MMAP2 events: 1 ( 2.5%) With this patch, it shows the original number now. $ perf record --buildid-mmap -o- true | perf inject -b --buildid-all | \ > perf report --stat -i- | grep MMAP2 MMAP2 events: 249 (86.5%) Committer testing: Before: $ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf inject -b | perf report --stat -i- | grep MMAP2 MMAP2 events: 58 (36.2%) $ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf report --stat -i- | grep MMAP2 MMAP2 events: 58 (36.2%) $ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf inject -b --buildid-all | perf report --stat -i- | grep MMAP2 MMAP2 events: 2 ( 1.9%) $ After: $ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf inject -b | perf report --stat -i- | grep MMAP2 MMAP2 events: 58 (29.3%) $ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf report --stat -i- | grep MMAP2 MMAP2 events: 58 (34.3%) $ perf record --buildid-mmap -o- perf stat --null sleep 1 2> /dev/null | perf inject -b --buildid-all | perf report --stat -i- | grep MMAP2 MMAP2 events: 58 (38.4%) $ Fixes:f7fc0d1c91("perf inject: Do not inject BUILD_ID record if MMAP2 has it") Signed-off-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230223070155.54251-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.