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

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Date:   Tue, 19 May 2020 09:54:22 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     ira.weiny@...el.com
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 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, 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().

Still testing ppc images.

Guenter