From: Pavel Machek <pavel@ucw.cz>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Randy Dunlap <rdunlap@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
linuxwifi@intel.com
Subject: Re: 4.19-rc[23] iwlwifi: BUG in swiotlb
Date: Sun, 16 Sep 2018 11:41:42 +0200 [thread overview]
Message-ID: <20180916094142.GB4299@amd> (raw)
In-Reply-To: <20180916093414.GA4299@amd>
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On Sun 2018-09-16 11:34:14, Pavel Machek wrote:
> Hi!
>
> > > Any ideas?
> >
> > Hmm. Is this new?
> >
> > > 2018-09-10T18:47:54.532837-07:00 dragon kernel: [ 31.472371] kernel BUG at ../kernel/dma/swiotlb.c:521!
> >
> > nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
> > [...]
> > BUG_ON(!nslots)
> >
> > > 2018-09-10T18:47:54.613655-07:00 dragon kernel: [ 31.490325] swiotlb_alloc+0x88/0x170
> > > 2018-09-10T18:47:54.613656-07:00 dragon kernel: [ 31.490329] ? __kmalloc+0x1cc/0x200
> > > 2018-09-10T18:47:54.613657-07:00 dragon kernel: [ 31.491652] iwl_pcie_txq_alloc+0x1d4/0x3b0 [iwlwifi]
> >
> > There are two calls to dma_alloc_coherent() here, should those even hit
> > swiotlb? The sizes of those should be
> > * 256 x 128 (32k)
> > * 32 x 256 (8k) [TFH, unlikely to be the case here]
> > * 256 x 256 (65k) [TFH]
> > * 32 x 64 (2k)
> > * 256 x 64 (16k)
> >
> >
> > IO_TLB_SHIFT is 11, so we get 2k alignment, so even the smallest size
> > (32*64) should result in nslots being 1?
> >
> > In fact, unless the driver passed *ZERO* as the size, this should never
> > happen (hence the BUG_ON), since ALIGN() would take care of rounding up
> > any smaller allocation here.
> >
> > Presumably you can reproduce this pretty easily (and I don't know what
> > specific model of NIC you have etc.), so perhaps you can do something
> > like this?
> >
> > https://p.sipsolutions.net/aa0dccd7a60fe176.txt
>
> That results in: ... if I'm not mistaken. Tested on top of today's
> mainline. (-rc3.95 :-)
Hold on. I was confused by my build system. Let me retry.
Are you sure you are not mistaking WARN and WARN_ON?
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2018-09-16 9:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-11 2:17 4.19-rc[23] iwlwifi: BUG in swiotlb Randy Dunlap
2018-09-11 7:32 ` Johannes Berg
2018-09-11 20:57 ` Randy Dunlap
2018-09-11 21:02 ` Johannes Berg
2018-09-16 9:34 ` Pavel Machek
2018-09-16 9:41 ` Pavel Machek [this message]
2018-09-16 9:55 ` Pavel Machek
2018-09-16 9:59 ` [PATCH] fix iwlwifi on old cards in v4.19 was " Pavel Machek
2018-09-16 10:12 ` [linuxwifi] " Grumbach, Emmanuel
2018-09-16 10:14 ` Grumbach, Emmanuel
2018-09-16 11:06 ` Pavel Machek
2018-10-07 0:44 ` Randy Dunlap
2018-10-07 0:56 ` Randy Dunlap
2018-09-16 22:27 ` Randy Dunlap
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