path: root/include/linux
diff options
authorOleg Nesterov <oleg@redhat.com>2013-04-30 15:28:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-30 17:04:06 -0700
commit403bad72b67d8b3f5a0240af5023adfa48132a65 (patch)
treed240a287cf7e64824dc6441f397b0290aa79738b /include/linux
parent66e5b7e1948cdbdca2b0cc6ddc6d69ee84583fb4 (diff)
coredump: only SIGKILL should interrupt the coredumping task
There are 2 well known and ancient problems with coredump/signals, and a lot of related bug reports: - do_coredump() clears TIF_SIGPENDING but of course this can't help if, say, SIGCHLD comes after that. In this case the coredump can fail unexpectedly. See for example wait_for_dump_helper()->signal_pending() check but there are other reasons. - At the same time, dumping a huge core on the slow media can take a lot of time/resources and there is no way to kill the coredumping task reliably. In particular this is not oom_kill-friendly. This patch tries to fix the 1st problem, and makes the preparation for the next changes. We add the new SIGNAL_GROUP_COREDUMP flag set by zap_threads() to indicate that this process dumps the core. prepare_signal() checks this flag and nacks any signal except SIGKILL. Note that this check tries to be conservative, in the long term we should probably treat the SIGNAL_GROUP_EXIT case equally but this needs more discussion. See marc.info/?l=linux-kernel&m=120508897917439 Notes: - recalc_sigpending() doesn't check SIGNAL_GROUP_COREDUMP. The patch assumes that dump_write/etc paths should never call it, but we can change it as well. - There is another source of TIF_SIGPENDING, freezer. This will be addressed separately. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Mandeep Singh Baines <msb@chromium.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Roland McGrath <roland@hack.frob.com> Cc: Tejun Heo <tj@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 54ddcb82cdd..a22baf83c20 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -626,6 +626,7 @@ struct signal_struct {
#define SIGNAL_STOP_STOPPED 0x00000001 /* job control stop in effect */
#define SIGNAL_STOP_CONTINUED 0x00000002 /* SIGCONT since WCONTINUED reap */
#define SIGNAL_GROUP_EXIT 0x00000004 /* group exit in progress */
+#define SIGNAL_GROUP_COREDUMP 0x00000008 /* coredump in progress */
* Pending notifications to parent.