From f45d85ff1f3f13d5b67fecb291edc6a771db0c53 Mon Sep 17 00:00:00 2001 From: HATAYAMA Daisuke Date: Tue, 30 Jun 2015 14:57:43 -0700 Subject: kernel/panic: call the 2nd crash_kexec() only if crash_kexec_post_notifiers is enabled For compatibility with the behaviour before the commit f06e5153f4ae2e ("kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers"), the 2nd crash_kexec() should be called only if crash_kexec_post_notifiers is enabled. Note that crash_kexec() returns immediately if kdump crash kernel is not loaded, so in this case, this patch makes no functionality change, but the point is to make it explicit, from the caller panic() side, that the 2nd crash_kexec() does nothing. Signed-off-by: HATAYAMA Daisuke Suggested-by: Ingo Molnar Cc: "Eric W. Biederman" Cc: Vivek Goyal Cc: Masami Hiramatsu Cc: Hidehiro Kawai Cc: Baoquan He Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/panic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 8136ad76e5fd..774614f72cbd 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -142,7 +142,8 @@ void panic(const char *fmt, ...) * Note: since some panic_notifiers can make crashed kernel * more unstable, it can increase risks of the kdump failure too. */ - crash_kexec(NULL); + if (crash_kexec_post_notifiers) + crash_kexec(NULL); bust_spinlocks(0); -- cgit v1.2.3-71-gd317 From 5375b708f2547f70cd2bee2fd8663ab7035f9551 Mon Sep 17 00:00:00 2001 From: HATAYAMA Daisuke Date: Tue, 30 Jun 2015 14:57:46 -0700 Subject: kernel/panic/kexec: fix "crash_kexec_post_notifiers" option issue in oops path Commit f06e5153f4ae2e ("kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers") introduced "crash_kexec_post_notifiers" kernel boot option, which toggles wheather panic() calls crash_kexec() before panic_notifiers and dump kmsg or after. The problem is that the commit overlooks panic_on_oops kernel boot option. If it is enabled, crash_kexec() is called directly without going through panic() in oops path. To fix this issue, this patch adds a check to "crash_kexec_post_notifiers" in the condition of kexec_should_crash(). Also, put a comment in kexec_should_crash() to explain not obvious things on this patch. Signed-off-by: HATAYAMA Daisuke Acked-by: Baoquan He Tested-by: Hidehiro Kawai Reviewed-by: Masami Hiramatsu Cc: Vivek Goyal Cc: Ingo Molnar Cc: Hidehiro Kawai Cc: Baoquan He Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 3 +++ kernel/kexec.c | 11 +++++++++++ kernel/panic.c | 2 +- 3 files changed, 15 insertions(+), 1 deletion(-) (limited to 'kernel/panic.c') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 5acf5b70866d..0dfa4e31563d 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -439,6 +439,9 @@ extern int panic_on_unrecovered_nmi; extern int panic_on_io_nmi; extern int panic_on_warn; extern int sysctl_panic_on_stackoverflow; + +extern bool crash_kexec_post_notifiers; + /* * Only to be used by arch init code. If the user over-wrote the default * CONFIG_PANIC_TIMEOUT, honor it. diff --git a/kernel/kexec.c b/kernel/kexec.c index 7a36fdcca5bf..a785c1015e25 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -84,6 +84,17 @@ struct resource crashk_low_res = { int kexec_should_crash(struct task_struct *p) { + /* + * If crash_kexec_post_notifiers is enabled, don't run + * crash_kexec() here yet, which must be run after panic + * notifiers in panic(). + */ + if (crash_kexec_post_notifiers) + return 0; + /* + * There are 4 panic() calls in do_exit() path, each of which + * corresponds to each of these 4 conditions. + */ if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops) return 1; return 0; diff --git a/kernel/panic.c b/kernel/panic.c index 774614f72cbd..04e91ff7560b 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -32,7 +32,7 @@ static unsigned long tainted_mask; static int pause_on_oops; static int pause_on_oops_flag; static DEFINE_SPINLOCK(pause_on_oops_lock); -static bool crash_kexec_post_notifiers; +bool crash_kexec_post_notifiers; int panic_on_warn __read_mostly; int panic_timeout = CONFIG_PANIC_TIMEOUT; -- cgit v1.2.3-71-gd317