Update comments (only) on page_table_lock and mmap_sem in arch/powerpc.
Removed the comment on page_table_lock from hash_huge_page: since it's
no longer taking page_table_lock itself, it's irrelevant whether others
are; but how it is safe (even against huge file truncation?) I can't say.
Signed-off-by: Hugh Dickins <[email protected]>
---
arch/powerpc/mm/hugetlbpage.c | 4 +---
arch/powerpc/mm/mem.c | 2 +-
arch/powerpc/mm/tlb_32.c | 6 ++++++
arch/powerpc/mm/tlb_64.c | 4 ++--
4 files changed, 10 insertions(+), 6 deletions(-)
--- mm06/arch/powerpc/mm/hugetlbpage.c 2005-11-07 07:39:05.000000000 +0000
+++ mm07/arch/powerpc/mm/hugetlbpage.c 2005-11-09 14:39:16.000000000 +0000
@@ -754,9 +754,7 @@ repeat:
}
/*
- * No need to use ldarx/stdcx here because all who
- * might be updating the pte will hold the
- * page_table_lock
+ * No need to use ldarx/stdcx here
*/
*ptep = __pte(new_pte & ~_PAGE_BUSY);
--- mm06/arch/powerpc/mm/mem.c 2005-11-07 07:39:05.000000000 +0000
+++ mm07/arch/powerpc/mm/mem.c 2005-11-09 14:39:16.000000000 +0000
@@ -491,7 +491,7 @@ EXPORT_SYMBOL(flush_icache_user_range);
* We use it to preload an HPTE into the hash table corresponding to
* the updated linux PTE.
*
- * This must always be called with the mm->page_table_lock held
+ * This must always be called with the pte lock held.
*/
void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
pte_t pte)
--- mm06/arch/powerpc/mm/tlb_32.c 2005-11-07 07:39:05.000000000 +0000
+++ mm07/arch/powerpc/mm/tlb_32.c 2005-11-09 14:39:16.000000000 +0000
@@ -149,6 +149,12 @@ void flush_tlb_mm(struct mm_struct *mm)
return;
}
+ /*
+ * It is safe to go down the mm's list of vmas when called
+ * from dup_mmap, holding mmap_sem. It would also be safe from
+ * unmap_region or exit_mmap, but not from vmtruncate on SMP -
+ * but it seems dup_mmap is the only SMP case which gets here.
+ */
for (mp = mm->mmap; mp != NULL; mp = mp->vm_next)
flush_range(mp->vm_mm, mp->vm_start, mp->vm_end);
FINISH_FLUSH;
--- mm06/arch/powerpc/mm/tlb_64.c 2005-11-07 07:39:05.000000000 +0000
+++ mm07/arch/powerpc/mm/tlb_64.c 2005-11-09 14:39:16.000000000 +0000
@@ -95,7 +95,7 @@ static void pte_free_submit(struct pte_f
void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf)
{
- /* This is safe as we are holding page_table_lock */
+ /* This is safe since tlb_gather_mmu has disabled preemption */
cpumask_t local_cpumask = cpumask_of_cpu(smp_processor_id());
struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
@@ -206,7 +206,7 @@ void __flush_tlb_pending(struct ppc64_tl
void pte_free_finish(void)
{
- /* This is safe as we are holding page_table_lock */
+ /* This is safe since tlb_gather_mmu has disabled preemption */
struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
if (*batchp == NULL)
-
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