Re: [alsa-devel] usb/sound/usx2y: warning in usb_stream_new/__alloc_pages_slowpath

[Takashi Iwai <tiwai@suse.de>]

On Mon, 02 Oct 2017 16:34:57 +0200,
Andrey Konovalov wrote:
> 
> On Mon, Oct 2, 2017 at 2:14 PM, Takashi Iwai <tiwai@suse.de> wrote:
> > On Fri, 22 Sep 2017 11:35:49 +0200,
> > Takashi Iwai wrote:
> >>
> >> On Thu, 21 Sep 2017 17:38:53 +0200,
> >> Andrey Konovalov wrote:
> >> >
> >> > Hi!
> >> >
> >> > I've got the following report while fuzzing the kernel with syzkaller.
> >> >
> >> > On commit ebb2c2437d8008d46796902ff390653822af6cc4 (Sep 18).
> >> >
> >> > ------------[ cut here ]------------
> >> > WARNING: CPU: 1 PID: 1846 at mm/page_alloc.c:3883
> >> > __alloc_pages_slowpath+0x1ef2/0x2d70
> >> > Modules linked in:
> >> > CPU: 1 PID: 1846 Comm: kworker/1:2 Not tainted
> >> > 4.14.0-rc1-42251-gebb2c2437d80 #215
> >> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> >> > Workqueue: usb_hub_wq hub_event
> >> > task: ffff8800643c18c0 task.stack: ffff88006b658000
> >> > RIP: 0010:trace_reclaim_retry_zone ./include/trace/events/oom.h:31
> >> > RIP: 0010:should_reclaim_retry mm/page_alloc.c:3783
> >> > RIP: 0010:__alloc_pages_slowpath+0x1ef2/0x2d70 mm/page_alloc.c:4039
> >> > RSP: 0018:ffff88006b65d938 EFLAGS: 00010246
> >> > RAX: 00000000ffffa666 RBX: 00000000014000c0 RCX: 0000000000000000
> >> > RDX: 0000000000000000 RSI: 0000000000000034 RDI: 000000000140c0c0
> >> > RBP: ffff88006b65e088 R08: 0000000000000000 R09: fffffffffff00f88
> >> > R10: 0000000000000000 R11: 0000000000000085 R12: ffff88006b65e130
> >> > R13: ffff88006b65e270 R14: ffff88006b65e0f0 R15: 000000000140c0c0
> >> > FS:  0000000000000000(0000) GS:ffff88006c900000(0000) knlGS:0000000000000000
> >> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >> > CR2: 0000000020829000 CR3: 0000000063cce000 CR4: 00000000000006e0
> >> > Call Trace:
> >> >  __alloc_pages_nodemask+0x921/0xf70 mm/page_alloc.c:4217
> >> >  alloc_pages_current+0xbb/0x1f0 mm/mempolicy.c:2035
> >> >  alloc_pages ./include/linux/gfp.h:505
> >> >  __get_free_pages+0x14/0x50 mm/page_alloc.c:4248
> >> >  usb_stream_new+0x50f/0x9f0 sound/usb/usx2y/usb_stream.c:214
> >>
> >> The warning itself should be harmless, indicating only that the driver
> >> tries to allocate too high-order memory pages.  The error path handles
> >> the allocation error gracefully, so basically we can suppress the
> >> warning by adding __GFP_NOWARN, in addition to a sanity check in the
> >> caller side.
> >>
> >> I've been traveling and will be traveling again in the next week, so
> >> I'll cook up once after back to work again.
> >
> > Andrey, could you check the patch below?  It should suppress the
> > spurious warnings.
> 
> Hi Takashi,
> 
> Your patch fixes the report triggered by my reproducer.
> 
> Thanks!
> 
> Tested-by: Andrey Konovalov <andreyknvl@google.com>

Great, queued to for-linus branch now.
Thanks!


Takashi