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author | Neil Horman <nhorman@tuxdriver.com> | 2009-09-23 15:56:56 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-24 07:21:00 -0700 |
commit | a293980c2e261bd5b0d2a77340dd04f684caff58 (patch) | |
tree | 69f2b2747548deafb146c18953ebce21ae1f02d4 /Documentation | |
parent | 725eae32df7754044809973034429a47e6035158 (diff) | |
download | linux-stable-a293980c2e261bd5b0d2a77340dd04f684caff58.tar.gz linux-stable-a293980c2e261bd5b0d2a77340dd04f684caff58.tar.bz2 linux-stable-a293980c2e261bd5b0d2a77340dd04f684caff58.zip |
exec: let do_coredump() limit the number of concurrent dumps to pipes
Introduce core pipe limiting sysctl.
Since we can dump cores to pipe, rather than directly to the filesystem,
we create a condition in which a user can create a very high load on the
system simply by running bad applications.
If the pipe reader specified in core_pattern is poorly written, we can
have lots of ourstandig resources and processes in the system.
This sysctl introduces an ability to limit that resource consumption.
core_pipe_limit defines how many in-flight dumps may be run in parallel,
dumps beyond this value are skipped and a note is made in the kernel log.
A special value of 0 in core_pipe_limit denotes unlimited core dumps may
be handled (this is the default value).
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reported-by: Earl Chew <earl_chew@agilent.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/sysctl/kernel.txt | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index b3d8b4922740..a028b92001ed 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -22,6 +22,7 @@ show up in /proc/sys/kernel: - callhome [ S390 only ] - auto_msgmni - core_pattern +- core_pipe_limit - core_uses_pid - ctrl-alt-del - dentry-state @@ -135,6 +136,27 @@ core_pattern is used to specify a core dumpfile pattern name. ============================================================== +core_pipe_limit: + +This sysctl is only applicable when core_pattern is configured to pipe core +files to user space helper a (when the first character of core_pattern is a '|', +see above). When collecting cores via a pipe to an application, it is +occasionally usefull for the collecting application to gather data about the +crashing process from its /proc/pid directory. In order to do this safely, the +kernel must wait for the collecting process to exit, so as not to remove the +crashing processes proc files prematurely. This in turn creates the possibility +that a misbehaving userspace collecting process can block the reaping of a +crashed process simply by never exiting. This sysctl defends against that. It +defines how many concurrent crashing processes may be piped to user space +applications in parallel. If this value is exceeded, then those crashing +processes above that value are noted via the kernel log and their cores are +skipped. 0 is a special value, indicating that unlimited processes may be +captured in parallel, but that no waiting will take place (i.e. the collecting +process is not guaranteed access to /proc/<crahing pid>/). This value defaults +to 0. + +============================================================== + core_uses_pid: The default coredump filename is "core". By setting |