5.4-stable review patch. If anyone has any objections, please let me know.
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From: John Ogness john.ogness@linutronix.de
[ Upstream commit 8076972468584d4a21dab9aa50e388b3ea9ad8c7 ]
console_trylock_spinning() may takeover the console lock from a schedulable context. Update @console_may_schedule to make sure it reflects a trylock acquire.
Reported-by: Mukesh Ojha quic_mojha@quicinc.com Closes: https://lore.kernel.org/lkml/20240222090538.23017-1-quic_mojha@quicinc.com Fixes: dbdda842fe96 ("printk: Add console owner and waiter logic to load balance console writes") Signed-off-by: John Ogness john.ogness@linutronix.de Reviewed-by: Mukesh Ojha quic_mojha@quicinc.com Reviewed-by: Petr Mladek pmladek@suse.com Link: https://lore.kernel.org/r/875xybmo2z.fsf@jogness.linutronix.de Signed-off-by: Petr Mladek pmladek@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/printk/printk.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index bb2198b40756d..ae1a97dd0c3cb 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1787,6 +1787,12 @@ static int console_trylock_spinning(void) */ mutex_acquire(&console_lock_dep_map, 0, 1, _THIS_IP_);
+ /* + * Update @console_may_schedule for trylock because the previous + * owner may have been schedulable. + */ + console_may_schedule = 0; + return 1; }