The patch titled
Subject: panic: unset panic_on_warn inside panic()
has been added to the -mm tree. Its filename is
panic-unset-panic_on_warn-inside-panic.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/panic-unset-panic_on_warn-inside-panic.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/panic-unset-panic_on_warn-inside-panic.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
Subject: panic: unset panic_on_warn inside panic()
In the current code, the following three places need to unset
panic_on_warn before calling panic() to avoid recursive panics:
kernel/kcsan/report.c: print_report()
kernel/sched/core.c: __schedule_bug()
mm/kfence/report.c: kfence_report_error()
In order to avoid copy-pasting "panic_on_warn = 0" all over the places, it
is better to move it inside panic() and then remove it from the other
places.
Link: https://lkml.kernel.org/r/1644324666-15947-4-git-send-email-yangtiezhu@xxxxxxxxxxx
Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Xuefeng Li <lixuefeng@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/panic.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
--- a/kernel/panic.c~panic-unset-panic_on_warn-inside-panic
+++ a/kernel/panic.c
@@ -185,6 +185,16 @@ void panic(const char *fmt, ...)
int old_cpu, this_cpu;
bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
+ if (panic_on_warn) {
+ /*
+ * This thread may hit another WARN() in the panic path.
+ * Resetting this prevents additional WARN() from panicking the
+ * system on this thread. Other threads are blocked by the
+ * panic_mutex in panic().
+ */
+ panic_on_warn = 0;
+ }
+
/*
* Disable local interrupts. This will prevent panic_smp_self_stop
* from deadlocking the first cpu that invokes the panic, since
@@ -576,16 +586,8 @@ void __warn(const char *file, int line,
if (regs)
show_regs(regs);
- if (panic_on_warn) {
- /*
- * This thread may hit another WARN() in the panic path.
- * Resetting this prevents additional WARN() from panicking the
- * system on this thread. Other threads are blocked by the
- * panic_mutex in panic().
- */
- panic_on_warn = 0;
+ if (panic_on_warn)
panic("panic_on_warn set ...\n");
- }
if (!regs)
dump_stack();
_
Patches currently in -mm which might be from yangtiezhu@xxxxxxxxxxx are
docs-kdump-update-description-about-sysfs-file-system-support.patch
docs-kdump-add-scp-example-to-write-out-the-dump-file.patch
panic-unset-panic_on_warn-inside-panic.patch
ubsan-no-need-to-unset-panic_on_warn-in-ubsan_epilogue.patch
kasan-no-need-to-unset-panic_on_warn-in-end_report.patch
