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Message-ID: <20200504210225.GW23230@ZenIV.linux.org.uk>
Date: Mon, 4 May 2020 22:02:25 +0100
From: Al Viro <viro@...iv.linux.org.uk>
To: Ira Weiny <ira.weiny@...el.com>
Cc: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Christian Koenig <christian.koenig@....com>,
Huang Rui <ray.huang@....com>,
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>,
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Subject: Re: [PATCH V2 00/11] Subject: Remove duplicated kmap code
On Mon, May 04, 2020 at 01:17:41PM -0700, Ira Weiny wrote:
> > || * arm: much, much worse. We have several files that pull linux/highmem.h:
> > || arch/arm/mm/cache-feroceon-l2.c, arch/arm/mm/cache-xsc3l2.c,
> > || arch/arm/mm/copypage-*.c, arch/arm/mm/dma-mapping.c, arch/arm/mm/flush.c,
> > || arch/arm/mm/highmem.c, arch/arm/probes/uprobes/core.c,
> > || arch/arm/include/asm/kvm_mmu.h (kmap_atomic_pfn()).
> > || Those are fine, but we also have this:
> > || arch/arm/include/asm/pgtable.h:200:#define __pte_map(pmd) (pte_t *)kmap_atomic(pmd_page(*(pmd)))
> > || arch/arm/include/asm/pgtable.h:208:#define pte_offset_map(pmd,addr) (__pte_map(pmd) + pte_index(addr))
> > || and sure as hell, asm/pgtable.h does *NOT* pull linux/highmem.h.
>
> It does not pull asm/highmem.h either...
No, but the users of those macros need to be considered.
> > || #define pte_offset_map(dir, addr) \
> > || ((pte_t *) kmap_atomic(pmd_page(*(dir))) + pte_index(addr))
> > || One pte_offset_map user in arch/microblaze:
> > || arch/microblaze/kernel/signal.c:207: ptep = pte_offset_map(pmdp, address);
> > || Messy, but doesn't require any changes (we have asm/pgalloc.h included
> > || there, and that pull linux/highmem.h).
>
> AFAICS asm/pgtable.h does not include asm/highmem.h here...
>
> So looks like arch/microblaze/kernel/signal.c will need linux/highmem.h
See above - line 39 in there is
#include <asm/pgalloc.h>
and line 14 in arch/microblaze/include/asm/pgalloc.h is
#include <linux/highmem.h>
It's conditional upon CONFIG_MMU in there, but so's the use of
pte_offset_map() in arch/microblaze/kernel/signal.c
So it shouldn't be a problem.
> > || * xtensa: users in arch/xtensa/kernel/pci-dma.c, arch/xtensa/mm/highmem.c,
> > || arch/xtensa/mm/cache.c and arch/xtensa/platforms/iss/simdisk.c (all pull
> > || linux/highmem.h).
>
> Actually
>
> arch/xtensa/mm/cache.c gets linux/highmem.h from linux/pagemap.h
>
> arch/xtensa/platforms/iss/simdisk.c may have an issue?
> linux/blkdev.h -> CONFIG_BLOCK -> linux/pagemap.h -> linux/highmem.h
> But simdisk.c requires BLK_DEV_SIMDISK -> CONFIG_BLOCK...
> <sigh>
Yep - see above re major chain of indirect includes conditional upon CONFIG_BLOCK
and its uses in places that only build with such configs. There's a plenty of
similar considerations outside of arch/*, unfortunately...
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