On Fri, Jun 13, 2014 at 09:02:53AM +0800, kbuild test robot wrote:
> tree: git://git.cmpxchg.org/linux-mmotm.git master
> head: a621774e0e7bbd9e8a024230af4704cc489bd40e
> commit: ef99d21ea4a246e56b9a55de5740655d30735f33 [78/178] madvise: cleanup swapin_walk_pmd_entry()
> config: make ARCH=i386 allyesconfig
>
> All warnings:
>
> In file included from arch/x86/include/asm/pgtable.h:432:0,
> from include/linux/mm.h:51,
> from include/linux/mman.h:4,
> from mm/madvise.c:8:
> mm/madvise.c: In function 'swapin_walk_pte_entry':
> >> arch/x86/include/asm/pgtable_32.h:53:42: warning: value computed is not used [-Wunused-value]
> ((pte_t *)kmap_atomic(pmd_page(*(dir))) + \
> ^
> mm/madvise.c:161:2: note: in expansion of macro 'pte_offset_map'
> pte_offset_map(walk->pmd, start & PMD_MASK);
Hmm, in the new pagewalk's scheme every callback function is called with
the relevant page table lock held, and we already have the pointers of pte
and ptl inside callbacks, so I thought that no need to recalculate them.
But from compiler's viewpoint, keeping pte_unmap_unlock()-pte_offset_map_lock()
relationship is important so I'll keep it in next post.
Thanks,
Naoya Horiguchi
>
> vim +53 arch/x86/include/asm/pgtable_32.h
>
> e621bd189 include/asm-x86/pgtable_32.h Dave Young 2008-08-20 37
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 38 /*
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 39 * Define this if things work differently on an i386 and an i486:
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 40 * it will (on an i486) warn about kernel memory accesses that are
> e49332bd1 include/asm-i386/pgtable.h Jesper Juhl 2005-05-01 41 * done without a 'access_ok(VERIFY_WRITE,..)'
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 42 */
> e49332bd1 include/asm-i386/pgtable.h Jesper Juhl 2005-05-01 43 #undef TEST_ACCESS_OK
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 44
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 45 #ifdef CONFIG_X86_PAE
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 46 # include <asm/pgtable-3level.h>
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 47 #else
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 48 # include <asm/pgtable-2level.h>
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 49 #endif
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 50
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 51 #if defined(CONFIG_HIGHPTE)
> cf840147d include/asm-x86/pgtable_32.h Joe Perches 2008-03-23 52 #define pte_offset_map(dir, address) \
> ece0e2b64 arch/x86/include/asm/pgtable_32.h Peter Zijlstra 2010-10-26 @53 ((pte_t *)kmap_atomic(pmd_page(*(dir))) + \
> cf840147d include/asm-x86/pgtable_32.h Joe Perches 2008-03-23 54 pte_index((address)))
> ece0e2b64 arch/x86/include/asm/pgtable_32.h Peter Zijlstra 2010-10-26 55 #define pte_unmap(pte) kunmap_atomic((pte))
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 56 #else
> cf840147d include/asm-x86/pgtable_32.h Joe Perches 2008-03-23 57 #define pte_offset_map(dir, address) \
> cf840147d include/asm-x86/pgtable_32.h Joe Perches 2008-03-23 58 ((pte_t *)page_address(pmd_page(*(dir))) + pte_index((address)))
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 59 #define pte_unmap(pte) do { } while (0)
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 60 #endif
> ^1da177e4 include/asm-i386/pgtable.h Linus Torvalds 2005-04-16 61
>
> :::::: The code at line 53 was first introduced by commit
> :::::: ece0e2b6406a995c371e0311190631ea34ad851a mm: remove pte_*map_nested()
>
> :::::: TO: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> :::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
>
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