linux-kernel - Re: [4.18 rc7] BUG: sleeping function called from invalid context at mm/slab.h:421

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Date:   Wed, 8 Aug 2018 19:40:41 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Vlastimil Babka <vbabka@...e.cz>, Jiri Slaby <jslaby@...e.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:     Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>,
        linux-mm@...ck.org, Petr Mladek <pmladek@...e.cz>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [4.18 rc7] BUG: sleeping function called from invalid context at
 mm/slab.h:421

Hello,

On (08/08/18 11:01), Vlastimil Babka wrote:
> On 08/08/2018 05:50 AM, Mikhail Gavrilov wrote:
> > Hi guys.
> > I am catched new bug.
> > Can anyone look?
> 
> fbcon_startup() calls kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL) so
> it tells slab it can sleep. The problem must be higher in the stack,
> CCing printk people.

Cc-ing fbcon/vt people. I'm not sure I know how exactly console
takeover is expected to work.

printk must be atomic, we can't sleep in console drivers [e.g. printk
from IRQs, etc.]

> > [226995.988988] BUG: sleeping function called from invalid context at
> > mm/slab.h:421
> > [226995.988988] in_atomic(): 1, irqs_disabled(): 1, pid: 22658, name: gsd-rfkill
> > [226995.988989] INFO: lockdep is turned off.
> > [226995.988989] irq event stamp: 0
> > [226995.988990] hardirqs last  enabled at (0): [<0000000000000000>]
> >        (null)
> > [226995.988991] hardirqs last disabled at (0): [<ffffffffa00b6b4a>]
> > copy_process.part.32+0x72a/0x1e60
> > [226995.988991] softirqs last  enabled at (0): [<ffffffffa00b6b4a>]
> > copy_process.part.32+0x72a/0x1e60
> > [226995.988992] softirqs last disabled at (0): [<0000000000000000>]
> >        (null)
> > [226995.988993] CPU: 6 PID: 22658 Comm: gsd-rfkill Tainted: G        W
> >         4.18.0-0.rc7.git1.1.fc29.x86_64 #1
> > [226995.988993] Hardware name: Gigabyte Technology Co., Ltd.
> > Z87M-D3H/Z87M-D3H, BIOS F11 08/12/2014
> > [226995.988994] Call Trace:
> > [226995.988994]  dump_stack+0x85/0xc0
> > [226995.988995]  ___might_sleep.cold.72+0xac/0xbc
> > [226995.988995]  kmem_cache_alloc_trace+0x202/0x2f0
> > [226995.988996]  ? fbcon_startup+0xae/0x300
> > [226995.988996]  fbcon_startup+0xae/0x300
> > [226995.988997]  do_take_over_console+0x6d/0x180
> > [226995.988997]  do_fbcon_takeover+0x58/0xb0
> > [226995.988997]  fbcon_output_notifier.cold.35+0x5/0x23
> > [226995.988998]  notifier_call_chain+0x39/0x90
> > [226995.988999]  vt_console_print+0x363/0x420
> > [226995.988999]  console_unlock+0x422/0x610
> > [226995.988999]  vprintk_emit+0x268/0x540
> > [226995.989000]  printk+0x58/0x6f
> > [226995.989000]  rfkill_fop_release.cold.16+0xc/0x11 [rfkill]
> > [226995.989001]  __fput+0xc7/0x250
> > [226995.989001]  task_work_run+0xa1/0xd0
> > [226995.989002]  exit_to_usermode_loop+0xd8/0xe0
> > [226995.989002]  do_syscall_64+0x1df/0x1f0
> > [226995.989003]  entry_SYSCALL_64_after_hwframe+0x49/0xbe

	-ss