On Fri, 2022-06-24 at 16:37 +0206, John Ogness wrote: > On 2022-06-24, John Ogness <john.ogness@xxxxxxxxxxxxx> wrote: > > As to this the actual problem reported in this thread, I believe > > this > > patch solves it: > > > > https://lore.kernel.org/lkml/20220609121709.12939-1-Jason@xxxxxxxxx > > There was a cleaner v2 later in the thread: > > https://lore.kernel.org/lkml/20220609123319.17576-1-Jason@xxxxxxxxx That's in tip, but pulling my bandaid off... [ 3.903338] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 [ 3.903340] in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 389, name: systemd-udevd [ 3.903340] preempt_count: 0, expected: 0 [ 3.903341] RCU nest depth: 1, expected: 1 [ 3.903342] CPU: 0 PID: 389 Comm: systemd-udevd Tainted: G E 5.19.0.g96ff3a1-tip-rt #8 3a0ec7519629dbce1c881d809a8600cfad8358ca [ 3.903344] Hardware name: MEDION MS-7848/MS-7848, BIOS M7848W08.20C 09/23/2013 [ 3.903345] Call Trace: [ 3.903346] <TASK> [ 3.903347] dump_stack_lvl+0x44/0x5c [ 3.903352] ? migrate_disable+0x37/0xa0 [ 3.903354] __might_resched+0x171/0x1c0 [ 3.903357] rt_spin_lock+0x2d/0x70 [ 3.903361] crng_make_state+0x80/0x1d0 [ 3.903364] _get_random_bytes.part.15+0x4e/0x120 [ 3.903366] ? nvkm_vmm_iter.constprop.11+0x311/0x860 [nouveau 9c7d46b64ad6b15f254390d4ef3bd03268a3030d] [ 3.903449] ? nvkm_vmm_sparse_unref_ptes+0x80/0x80 [nouveau 9c7d46b64ad6b15f254390d4ef3bd03268a3030d] [ 3.903518] ? gf100_vmm_pgt_sgl+0x230/0x230 [nouveau 9c7d46b64ad6b15f254390d4ef3bd03268a3030d] [ 3.903588] default_pointer+0x2a0/0x2d0 [ 3.903591] vsnprintf+0x35e/0x4c0 [ 3.903593] ? gf100_gr_object_new+0x2b/0x70 [nouveau 9c7d46b64ad6b15f254390d4ef3bd03268a3030d] [ 3.903669] va_format.isra.16+0x6e/0xa0 [ 3.903670] vsnprintf+0x35e/0x4c0 [ 3.903673] vprintk_store+0x140/0x540 Bandaid: printk: fix RT vprintk_store() might sleep splat RT can't call vsnprintf() with IRQs disabled, so disable migration and move the printk_enter_irqsave() call down to where it's needed. Signed-off-by: Mike Galbraith <efault@xxxxxx> --- kernel/printk/printk.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2277,8 +2277,7 @@ int vprintk_store(int facility, int leve int ret = 0; u64 ts_nsec; - if (!printk_enter_irqsave(recursion_ptr, irqflags)) - return 0; + migrate_disable(); /* * Since the duration of printk() can vary depending on the message @@ -2313,6 +2312,11 @@ int vprintk_store(int facility, int leve if (dev_info) flags |= LOG_NEWLINE; + if (!printk_enter_irqsave(recursion_ptr, irqflags)) { + migrate_enable(); + return 0; + } + if (flags & LOG_CONT) { prb_rec_init_wr(&r, reserve_size); if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) { @@ -2369,6 +2373,7 @@ int vprintk_store(int facility, int leve ret = text_len + trunc_msg_len; out: printk_exit_irqrestore(recursion_ptr, irqflags); + migrate_enable(); return ret; }
