diff options
| author | Gerald Schaefer <gerald.schaefer@de.ibm.com> | 2012-10-08 16:30:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-09 16:22:30 +0900 |
| commit | 75077afbec1ac89178c1542b23a70d0f960b0aaf (patch) | |
| tree | 843b8a7175de7a9a2dca37d877cd742121f4b627 /arch/s390/mm/gup.c | |
| parent | 8e72033f2a489b6c98c4e3c7cc281b1afd6cb85c (diff) | |
thp, s390: thp splitting backend for s390
This patch is part of the architecture backend for thp on s390. It
provides the functions related to thp splitting, including serialization
against gup. Unlike other archs, pmdp_splitting_flush() cannot use a tlb
flushing operation to serialize against gup on s390, because that wouldn't
be stopped by the disabled IRQs. So instead, smp_call_function() is
called with an empty function, which will have the expected effect.
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/s390/mm/gup.c')
| -rw-r--r-- | arch/s390/mm/gup.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index eeaf8023851..60acb93a468 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -115,7 +115,16 @@ static inline int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, pmd = *pmdp; barrier(); next = pmd_addr_end(addr, end); - if (pmd_none(pmd)) + /* + * The pmd_trans_splitting() check below explains why + * pmdp_splitting_flush() has to serialize with + * smp_call_function() against our disabled IRQs, to stop + * this gup-fast code from running while we set the + * splitting bit in the pmd. Returning zero will take + * the slow path that will call wait_split_huge_page() + * if the pmd is still in splitting state. + */ + if (pmd_none(pmd) || pmd_trans_splitting(pmd)) return 0; if (unlikely(pmd_huge(pmd))) { if (!gup_huge_pmd(pmdp, pmd, addr, next, |