printk: Avoid livelock with heavy printk during panic

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During panic(), if another CPU is writing heavily the kernel log (e.g.
via /dev/kmsg), then the panic CPU may livelock writing out its messages
to the console. Note when too many messages are dropped during panic and
suppress further printk, except from the panic CPU. This could result in
some important messages being dropped. However, messages are already
being dropped, so this approach at least prevents a livelock.

Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220202171821.179394-4-stephen.s.brennan@oracle.com

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Stephen Brennan 2022-02-02 09:18:20 -08:00 • committed by Petr Mladek

parent d51507098f

commit 13fb0f74d7

1 changed files with 15 additions and 0 deletions

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kernel/printk/printk.c

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