linux-kernel - Re: [PATCH V3 07/15] arch/kunmap_atomic: Consolidate duplicate code

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Date:   Mon, 18 May 2020 11:11:08 -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>,
        Christoph Hellwig <hch@....de>,
        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>
Subject: Re: [PATCH V3 07/15] arch/kunmap_atomic: Consolidate duplicate code

On Sun, May 17, 2020 at 09:29:32PM -0700, Guenter Roeck wrote:
> On Sun, May 17, 2020 at 08:49:39PM -0700, Ira Weiny wrote:
> > On Sat, May 16, 2020 at 03:33:06PM -0700, Guenter Roeck wrote:
> > > On Thu, May 07, 2020 at 07:59:55AM -0700, ira.weiny@...el.com wrote:
> > > > From: Ira Weiny <ira.weiny@...el.com>
> > > > 
> > > > Every single architecture (including !CONFIG_HIGHMEM) calls...
> > > > 
> > > > 	pagefault_enable();
> > > > 	preempt_enable();
> > > > 
> > > > ... before returning from __kunmap_atomic().  Lift this code into the
> > > > kunmap_atomic() macro.
> > > > 
> > > > While we are at it rename __kunmap_atomic() to kunmap_atomic_high() to
> > > > be consistent.
> > > > 
> > > > Reviewed-by: Christoph Hellwig <hch@....de>
> > > > Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> > > 
> > > This patch results in:
> > > 
> > > Starting init: /bin/sh exists but couldn't execute it (error -14)
> > > 
> > > when trying to boot microblazeel:petalogix-ml605 in qemu.
> > 
> > Thanks for the report.  I'm not readily seeing the issue.
> > 
> > Do you have a kernel config?  Specifically is CONFIG_HIGHMEM set?
> > 
> See below. Yes, CONFIG_HIGHMEM is set.
> 
> The scripts used to build and boot the image are at:
> 
> https://github.com/groeck/linux-build-test/tree/master/rootfs/microblazeel
> 
> Hope this helps,

Thank you ...

Could you try the following patch?


commit 82c284b2bb74ca195dfcd35b70a175f010b9fd46 (HEAD -> lm-kmap17)
Author: Ira Weiny <ira.weiny@...el.com>
Date:   Mon May 18 11:01:10 2020 -0700

    microblaze/kmap: Don't enable pagefault/preempt twice
    
    The kunmap_atomic clean up failed to remove the pagefault/preempt
    enables on this path.
    
    Fixes: bee2128a09e6 ("arch/kunmap_atomic: consolidate duplicate code")
    Signed-off-by: Ira Weiny <ira.weiny@...el.com>

diff --git a/arch/microblaze/mm/highmem.c b/arch/microblaze/mm/highmem.c
index ee8a422b2b76..92e0890416c9 100644
--- a/arch/microblaze/mm/highmem.c
+++ b/arch/microblaze/mm/highmem.c
@@ -57,11 +57,8 @@ void kunmap_atomic_high(void *kvaddr)
        int type;
        unsigned int idx;
 
-       if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
-               pagefault_enable();
-               preempt_enable();
+       if (vaddr < __fix_to_virt(FIX_KMAP_END))
                return;
-       }
 
        type = kmap_atomic_idx();