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Date: Fri, 25 May 2007 22:12:55 +0900 From: "Kawai, Hidehiro" <hidehiro.kawai.ez@...achi.com> To: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org Cc: dhowells@...hat.com, holt@....com, alan@...rguk.ukuu.org.uk, masami.hiramatsu.pt@...achi.com, yumiko.sugita.yf@...achi.com, soshima@...hat.com, haoki@...hat.com Subject: [PATCH 7/7] documentation for /proc/pid/coredump_filter This patch adds the documentation for /proc/<pid>/coredump_filter. Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com> --- Documentation/filesystems/proc.txt | 38 +++++++++++++++++++++++++++ 1 files changed, 38 insertions(+) Index: linux-2.6.22-rc2-mm1/Documentation/filesystems/proc.txt =================================================================== --- linux-2.6.22-rc2-mm1.orig/Documentation/filesystems/proc.txt +++ linux-2.6.22-rc2-mm1/Documentation/filesystems/proc.txt @@ -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 ------------------------------------------------------------------------------ Preface @@ -2135,4 +2136,41 @@ those 64-bit counters, process A could s 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 wnat 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 + ------------------------------------------------------------------------------ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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