From bb90110dcb9e93bf79e3c988abc6cbcabd46d57f Mon Sep 17 00:00:00 2001 From: "Kawai, Hidehiro" Date: Thu, 19 Jul 2007 01:48:31 -0700 Subject: [PATCH] coredump masking: documentation for /proc/pid/coredump_filter This patch adds the documentation for /proc//coredump_filter. Signed-off-by: Hidehiro Kawai Cc: Alan Cox Cc: David Howells Cc: Hugh Dickins Cc: Nick Piggin Cc: "Randy.Dunlap" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 38 ++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 72e247ef6f..4a37e25e69 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -42,6 +42,7 @@ Table of Contents 2.12 /proc//oom_adj - Adjust the oom-killer score 2.13 /proc//oom_score - Display current oom-killer score 2.14 /proc//io - Display the IO accounting fields + 2.15 /proc//coredump_filter - Core dump filtering settings ------------------------------------------------------------------------------ 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//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//coredump_filter allows you to customize which memory segments +will be dumped when the 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 + ------------------------------------------------------------------------------ -- 2.39.5