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authorLinus Torvalds <torvalds@linux-foundation.org>2022-05-25 10:32:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-05-25 10:32:08 -0700
commit537e62c865dcb9b91d07ed83f8615b71fa0b51bb (patch)
tree6874d3c223e11b6a03da735caab862c06412ede1 /kernel/panic.c
parent2e17ce1106e04a7f3a83796ec623881487f75dd3 (diff)
parent1c6fd59943a630f087b4b3089aefdcb0bf43cca0 (diff)
Merge tag 'printk-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek: - Offload writing printk() messages on consoles to per-console kthreads. It prevents soft-lockups when an extensive amount of messages is printed. It was observed, for example, during boot of large systems with a lot of peripherals like disks or network interfaces. It prevents live-lockups that were observed, for example, when messages about allocation failures were reported and a CPU handled consoles instead of reclaiming the memory. It was hard to solve even with rate limiting because it would need to take into account the amount of messages and the speed of all consoles. It is a must to have for real time. Otherwise, any printk() might break latency guarantees. The per-console kthreads allow to handle each console on its own speed. Slow consoles do not longer slow down faster ones. And printk() does not longer unpredictably slows down various code paths. There are situations when the kthreads are either not available or not reliable, for example, early boot, suspend, or panic. In these situations, printk() uses the legacy mode and tries to handle consoles immediately. - Add documentation for the printk index. * tag 'printk-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk, tracing: fix console tracepoint printk: remove @console_locked printk: extend console_lock for per-console locking printk: add kthread console printers printk: add functions to prefer direct printing printk: add pr_flush() printk: move buffer definitions into console_emit_next_record() caller printk: refactor and rework printing logic printk: add con_printk() macro for console details printk: call boot_delay_msec() in printk_delay() printk: get caller_id/timestamp after migration disable printk: wake waiters for safe and NMI contexts printk: wake up all waiters printk: add missing memory barrier to wake_up_klogd() printk: cpu sync always disable interrupts printk: rename cpulock functions printk/index: Printk index feature documentation MAINTAINERS: Add printk indexing maintainers on mention of printk_index
Diffstat (limited to 'kernel/panic.c')
-rw-r--r--kernel/panic.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/panic.c b/kernel/panic.c
index 8355b19676f8..6737b2332275 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -579,6 +579,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
{
disable_trace_on_warning();
+ printk_prefer_direct_enter();
+
if (file)
pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
raw_smp_processor_id(), current->pid, file, line,
@@ -608,6 +610,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
/* Just a warning, don't kill lockdep. */
add_taint(taint, LOCKDEP_STILL_OK);
+
+ printk_prefer_direct_exit();
}
#ifndef __WARN_FLAGS