console_lock is the outermost subsystem lock for a lot of subsystems, which means get/put_user must nest within. Which means it cannot be acquired somewhere deeply nested in other locks, and most definitely not while holding fs locks potentially needed to resolve faults. console_trylock is the best we can do here. Including printk folks since even trylock feels realyl iffy here to me. Reported-by: syzbot+6cebc1af246fe020a2f0@xxxxxxxxxxxxxxxxxxxxxxxxx References: https://lore.kernel.org/dri-devel/00000000000026c1ff061cd0de12@xxxxxxxxxx/ Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> Fixes: a8f354284304 ("bcachefs: bch2_print_string_as_lines()") Cc: <stable@xxxxxxxxxxxxxxx> # v6.7+ Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx> Cc: Brian Foster <bfoster@xxxxxxxxxx> Cc: linux-bcachefs@xxxxxxxxxxxxxxx Cc: Petr Mladek <pmladek@xxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: John Ogness <john.ogness@xxxxxxxxxxxxx> Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> --- fs/bcachefs/util.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c index de331dec2a99..02381c653603 100644 --- a/fs/bcachefs/util.c +++ b/fs/bcachefs/util.c @@ -255,13 +255,14 @@ void bch2_prt_u64_base2(struct printbuf *out, u64 v) void bch2_print_string_as_lines(const char *prefix, const char *lines) { const char *p; + int locked; if (!lines) { printk("%s (null)\n", prefix); return; } - console_lock(); + locked = console_trylock(); while (1) { p = strchrnul(lines, '\n'); printk("%s%.*s\n", prefix, (int) (p - lines), lines); @@ -269,7 +270,8 @@ void bch2_print_string_as_lines(const char *prefix, const char *lines) break; lines = p + 1; } - console_unlock(); + if (locked) + console_unlock(); } int bch2_save_backtrace(bch_stacktrace *stack, struct task_struct *task, unsigned skipnr, -- 2.45.2
