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coredump masking: documentation for /proc/pid/coredump_filter

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This patch adds the documentation for /proc/<pid>/coredump_filter.

Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kawai, Hidehiro 2007-07-19 01:48:31 -07:00 committed by Linus Torvalds
parent ee78b0a61f
commit bb90110dcb
1 changed files with 38 additions and 0 deletions
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38
Documentation/filesystems/proc.txt
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@ -42,6 +42,7 @@ Table of Contents
2.12 /proc/<pid>/oom_adj - Adjust the oom-killer score
2.13 /proc/<pid>/oom_score - Display current oom-killer score
2.14 /proc/<pid>/io - Display the IO accounting fields
2.15 /proc/<pid>/coredump_filter - Core dump filtering settings
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Preface
@ -2184,4 +2185,41 @@ those 64-bit counters, process A could see an intermediate result.
More information about this can be found within the taskstats documentation in
Documentation/accounting.
2.15 /proc/<pid>/coredump_filter - Core dump filtering settings
---------------------------------------------------------------
When a process is dumped, all anonymous memory is written to a core file as
long as the size of the core file isn't limited. But sometimes we don't want
to dump some memory segments, for example, huge shared memory. Conversely,
sometimes we want to save file-backed memory segments into a core file, not
only the individual files.
/proc/<pid>/coredump_filter allows you to customize which memory segments
will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
of memory types. If a bit of the bitmask is set, memory segments of the
corresponding memory type are dumped, otherwise they are not dumped.
The following 4 memory types are supported:
- (bit 0) anonymous private memory
- (bit 1) anonymous shared memory
- (bit 2) file-backed private memory
- (bit 3) file-backed shared memory
Note that MMIO pages such as frame buffer are never dumped and vDSO pages
are always dumped regardless of the bitmask status.
Default value of coredump_filter is 0x3; this means all anonymous memory
segments are dumped.
If you don't want to dump all shared memory segments attached to pid 1234,
write 1 to the process's proc file.
$ echo 0x1 > /proc/1234/coredump_filter
When a new process is created, the process inherits the bitmask status from its
parent. It is useful to set up coredump_filter before the program runs.
For example:
$ echo 0x7 > /proc/self/coredump_filter
$ ./some_program
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