The patch titled
Subject: core_pattern: add CPU specifier
has been added to the -mm mm-nonmm-unstable branch. Its filename is
core_pattern-add-cpu-specifier.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/core_pattern-add-cpu-specifier.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Oleksandr Natalenko <oleksandr@xxxxxxxxxx>
Subject: core_pattern: add CPU specifier
Date: Sat, 3 Sep 2022 08:43:30 +0200
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@xxxxxxxxxx
Signed-off-by: Oleksandr Natalenko <oleksandr@xxxxxxxxxx>
Suggested-by: Renaud Métrich <rmetrich@xxxxxxxxxx>
Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Eric W . Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Grzegorz Halat <ghalat@xxxxxxxxxx>
Cc: "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Jason A. Donenfeld <Jason@xxxxxxxxx>
Cc: Joel Savitz <jsavitz@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Stephen Kitt <steve@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/sysctl/kernel.rst | 1 +
fs/coredump.c | 5 +++++
include/linux/coredump.h | 1 +
3 files changed, 7 insertions(+)
--- a/Documentation/admin-guide/sysctl/kernel.rst~core_pattern-add-cpu-specifier
+++ a/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
%<OTHER> both are dropped
======== ==========================================
--- a/fs/coredump.c~core_pattern-add-cpu-specifier
+++ a/fs/coredump.c
@@ -325,6 +325,10 @@ static int format_corename(struct core_n
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;
}
@@ -535,6 +539,7 @@ void do_coredump(const kernel_siginfo_t
*/
.mm_flags = mm->flags,
.vma_meta = NULL,
+ .cpu = raw_smp_processor_id(),
};
audit_core_dumps(siginfo->si_signo);
--- a/include/linux/coredump.h~core_pattern-add-cpu-specifier
+++ a/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;
_
Patches currently in -mm which might be from oleksandr@xxxxxxxxxx are
core_pattern-add-cpu-specifier.patch
