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

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Message-ID: <20200520051315.GA3660833@iweiny-DESK2.sc.intel.com>
Date:   Tue, 19 May 2020 22:13:16 -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 ]
> > > 
> > > Code path leading to that message is different but always the same
> > > from free_unref_page().

Actually it occurs to me that the patch consolidating kmap_prot is odd for
sparc 32 bit...

Its a long shot but could you try reverting this patch?

4ea7d2419e3f kmap: consolidate kmap_prot definitions

Alternately I will need to figure out how to run the sparc on qemu here...

Thanks very much for all the testing though!  :-D

Ira

> > > 
> > > Still testing ppc images.
> > > 
> 
> ppc image tests are passing with this patch.
> 
> Guenter