linux-kernel - Re: [PATCH 2/2] mm: simplify follow

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Date:   Wed, 11 Nov 2020 22:12:54 +1100
From:   Stephen Rothwell <sfr@...b.auug.org.au>
To:     Christoph Hellwig <hch@....de>
Cc:     Christian Borntraeger <borntraeger@...ibm.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        akpm@...ux-foundation.org, dan.j.williams@...el.com,
        daniel@...ll.ch, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-nvdimm@...ts.01.org, Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        clang-built-linux@...glegroups.com,
        Linux-Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: [PATCH 2/2] mm: simplify follow_pte{,pmd}

Hi Christoph,

On Wed, 11 Nov 2020 09:28:42 +0100 Christoph Hellwig <hch@....de> wrote:
>
> On Wed, Nov 11, 2020 at 09:26:20AM +0100, Christian Borntraeger wrote:
> > 
> > On 11.11.20 09:18, Christoph Hellwig wrote:  
> > > On Tue, Nov 10, 2020 at 06:21:22PM -0800, Nick Desaulniers wrote:  
> > >> Sorry, I think this patch may be causing a regression for us for s390?
> > >> https://travis-ci.com/github/ClangBuiltLinux/continuous-integration/jobs/432129279#L768
> > >>
> > >> (via https://lore.kernel.org/linux-mm/20201029101432.47011-3-hch@lst.de)  
> > > 
> > > Hmm, the call to follow_pte_pmd in the s390 code does not actually exist
> > > in my tree.  
> > 
> > This is a mid-air collision in linux-next between
> > 
> > b2ff5796a934 ("mm: simplify follow_pte{,pmd}")
> > a67a88b0b8de ("s390/pci: remove races against pte updates")  
> 
> Ah.  The fixup is trivial: just s/follow_pte_pmd/follow_pte/.

ok, so tomorrow I will add the following to the merge of the
akpm-current tree:

From: Stephen Rothwell <sfr@...b.auug.org.au>
Date: Wed, 11 Nov 2020 22:08:32 +1100
Subject: [PATCH] merge fix for "s390/pci: remove races against pte updates"

Signed-off-by: Stephen Rothwell <sfr@...b.auug.org.au>
---
 arch/s390/pci/pci_mmio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/pci/pci_mmio.c b/arch/s390/pci/pci_mmio.c
index 1a6adbc68ee8..4a4993837413 100644
--- a/arch/s390/pci/pci_mmio.c
+++ b/arch/s390/pci/pci_mmio.c
@@ -173,7 +173,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr,
 	if (!(vma->vm_flags & VM_WRITE))
 		goto out_unlock_mmap;
 
-	ret = follow_pte_pmd(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl);
+	ret = follow_pte(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl);
 	if (ret)
 		goto out_unlock_mmap;
 
@@ -317,7 +317,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr,
 	if (!(vma->vm_flags & VM_WRITE))
 		goto out_unlock_mmap;
 
-	ret = follow_pte_pmd(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl);
+	ret = follow_pte(vma->vm_mm, mmio_addr, NULL, &ptep, NULL, &ptl);
 	if (ret)
 		goto out_unlock_mmap;
 
-- 
2.29.2

-- 
Cheers,
Stephen Rothwell

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