linux-kernel - Re: [PATCH] arch/{mips,sparc,microblaze,powerpc}: Don't enable pagefault/preempt twice

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Date:   Tue, 19 May 2020 22:02:34 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        "David S. Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-snps-arc@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-csky@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, sparclinux@...r.kernel.org,
        linux-xtensa@...ux-xtensa.org, dri-devel@...ts.freedesktop.org,
        Christian Koenig <christian.koenig@....com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH] arch/{mips,sparc,microblaze,powerpc}: Don't enable
 pagefault/preempt twice

On Tue, May 19, 2020 at 12:42:15PM -0700, Guenter Roeck wrote:
> On Tue, May 19, 2020 at 11:40:32AM -0700, Ira Weiny wrote:
> > On Tue, May 19, 2020 at 09:54:22AM -0700, Guenter Roeck wrote:
> > > On Mon, May 18, 2020 at 11:48:43AM -0700, ira.weiny@...el.com wrote:
> > > > From: Ira Weiny <ira.weiny@...el.com>
> > > > 
> > > > The kunmap_atomic clean up failed to remove one set of pagefault/preempt
> > > > enables when vaddr is not in the fixmap.
> > > > 
> > > > Fixes: bee2128a09e6 ("arch/kunmap_atomic: consolidate duplicate code")
> > > > Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> > > 
> > > microblazeel works with this patch,
> > 
> > Awesome...  Andrew in my rush yesterday I should have put a reported by on the
> > patch for Guenter as well.
> > 
> > Sorry about that Guenter,
> 
> No worries.
> 
> > Ira
> > 
> > > as do the nosmp sparc32 boot tests,
> > > but sparc32 boot tests with SMP enabled still fail with lots of messages
> > > such as:
> > > 
> > > BUG: Bad page state in process swapper/0  pfn:006a1
> > > page:f0933420 refcount:0 mapcount:1 mapping:(ptrval) index:0x1
> > > flags: 0x0()
> > > raw: 00000000 00000100 00000122 00000000 00000001 00000000 00000000 00000000
> > > page dumped because: nonzero mapcount
> > > Modules linked in:
> > > CPU: 0 PID: 1 Comm: swapper/0 Tainted: G    B             5.7.0-rc6-next-20200518-00002-gb178d2d56f29 #1
> > > [f00e7ab8 :
> > > bad_page+0xa8/0x108 ]
> > > [f00e8b54 :
> > > free_pcppages_bulk+0x154/0x52c ]
> > > [f00ea024 :
> > > free_unref_page+0x54/0x6c ]
> > > [f00ed864 :
> > > free_reserved_area+0x58/0xec ]
> > > [f0527104 :
> > > kernel_init+0x14/0x110 ]
> > > [f000b77c :
> > > ret_from_kernel_thread+0xc/0x38 ]
> > > [00000000 :
> > > 0x0 ]

I'm really not seeing how this is related to the kmap clean up.

But just to make sure I'm trying to run your environment for sparc and having
less luck than with microblaze.

Could you give me the command which is failing above?

Ira

> > > 
> > > Code path leading to that message is different but always the same
> > > from free_unref_page().
> > > 
> > > Still testing ppc images.
> > > 
> 
> ppc image tests are passing with this patch.
> 
> Guenter