This series tightens the rules for ACCESS_ONCE to only work
on scalar types. It also contains the necessary fixups as
indicated by build bots of linux-next.
Now everything is in place to prevent new non-scalar users
of ACCESS_ONCE and we can continue to convert code to
READ_ONCE/WRITE_ONCE.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux
Pull ACCESS_ONCE() rule tightening from Christian Borntraeger:
"Tighten rules for ACCESS_ONCE
This series tightens the rules for ACCESS_ONCE to only work on scalar
types. It also contains the necessary fixups as indicated by build
bots of linux-next. Now everything is in place to prevent new
non-scalar users of ACCESS_ONCE and we can continue to convert code to
READ_ONCE/WRITE_ONCE"
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux:
kernel: Fix sparse warning for ACCESS_ONCE
next: sh: Fix compile error
kernel: tighten rules for ACCESS ONCE
mm/gup: Replace ACCESS_ONCE with READ_ONCE
x86/spinlock: Leftover conversion ACCESS_ONCE->READ_ONCE
x86/xen/p2m: Replace ACCESS_ONCE with READ_ONCE
ppc/hugetlbfs: Replace ACCESS_ONCE with READ_ONCE
ppc/kvm: Replace ACCESS_ONCE with READ_ONCE
This allows the get_user_pages_fast slow path to release the mmap_sem
before blocking.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 927609d622 ("kernel: tighten rules for ACCESS ONCE") results in a
compile failure for sh builds with CONFIG_X2TLB enabled.
arch/sh/mm/gup.c: In function 'gup_get_pte':
arch/sh/mm/gup.c:20:2: error: invalid initializer
make[1]: *** [arch/sh/mm/gup.o] Error 1
Replace ACCESS_ONCE with READ_ONCE to fix the problem.
Fixes: 927609d622 ("kernel: tighten rules for ACCESS ONCE")
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This patch avoids fuse hangs on sh4 by flushing the cache on
get_user_pages_fast(). This is not necessary a good thing to do, but
get_user_pages() does this, so get_user_pages_fast() should too.
Please note the patch for mips arch that addresses the similar problem:
https://kernel.googlesource.com/pub/scm/linux/kernel/git/ralf/linux/+/linux-3.4.50%5E!/#F0
They basically simply disable get_user_pages_fast() at all, using a
fall-back to get_user_pages(). But my fix is different, it adds an
explicit cache flushes.
Signed-off-by: Stas Sergeev <stsp@users.sourceforge.net>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Kamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
