From 8603b6f58637ce196d68f7749633ea81af196d66 Mon Sep 17 00:00:00 2001 From: Oleksandr Natalenko Date: Sat, 3 Sep 2022 08:43:30 +0200 Subject: [PATCH] core_pattern: add CPU specifier MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Statistically, in a large deployment regular segfaults may indicate a CPU issue. Currently, it is not possible to find out what CPU the segfault happened on. There are at least two attempts to improve segfault logging with this regard, but they do not help in case the logs rotate. Hence, lets make sure it is possible to permanently record a CPU the task ran on using a new core_pattern specifier. Link: https://lkml.kernel.org/r/20220903064330.20772-1-oleksandr@redhat.com Signed-off-by: Oleksandr Natalenko Suggested-by: Renaud Métrich Reviewed-by: Oleg Nesterov Cc: Alexander Viro Cc: "Eric W . Biederman" Cc: Grzegorz Halat Cc: "Guilherme G. Piccoli" Cc: "Huang, Ying" Cc: Jason A. Donenfeld Cc: Joel Savitz Cc: Jonathan Corbet Cc: Kees Cook Cc: Laurent Dufour Cc: Luis Chamberlain Cc: Rob Herring Cc: Stephen Kitt Cc: Will Deacon Cc: Xiaoming Ni Signed-off-by: Andrew Morton --- Documentation/admin-guide/sysctl/kernel.rst | 1 + fs/coredump.c | 5 +++++ include/linux/coredump.h | 1 + 3 files changed, 7 insertions(+) diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 98d1b19..3b618a4 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -174,6 +174,7 @@ core_pattern %f executable filename %E executable path %c maximum size of core file by resource limit RLIMIT_CORE + %C CPU the task ran on % both are dropped ======== ========================================== diff --git a/fs/coredump.c b/fs/coredump.c index 7bad778..3e8630c 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -325,6 +325,10 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm, err = cn_printf(cn, "%lu", rlimit(RLIMIT_CORE)); break; + /* CPU the task ran on */ + case 'C': + err = cn_printf(cn, "%d", cprm->cpu); + break; default: break; } @@ -534,6 +538,7 @@ void do_coredump(const kernel_siginfo_t *siginfo) */ .mm_flags = mm->flags, .vma_meta = NULL, + .cpu = raw_smp_processor_id(), }; audit_core_dumps(siginfo->si_signo); diff --git a/include/linux/coredump.h b/include/linux/coredump.h index 08a1d3e..191dcf5 100644 --- a/include/linux/coredump.h +++ b/include/linux/coredump.h @@ -22,6 +22,7 @@ struct coredump_params { struct file *file; unsigned long limit; unsigned long mm_flags; + int cpu; loff_t written; loff_t pos; loff_t to_skip; -- 2.7.4