diff options
| author | Anton Blanchard <anton@samba.org> | 2011-09-14 09:43:15 +0000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2011-09-20 15:53:23 +1000 |
| commit | 8bdafa39a47265bc029838b35cc6585f69224afa (patch) | |
| tree | cade05d9d67d3c6c421f46012961a46dacae5d70 /arch/powerpc/mm/mmu_context_hash64.c | |
| parent | a11940978bd598e65996b4f807cf4904793f7025 (diff) | |
powerpc: Fix deadlock in icswx code
The icswx code introduced an A-B B-A deadlock:
CPU0 CPU1
---- ----
lock(&anon_vma->mutex);
lock(&mm->mmap_sem);
lock(&anon_vma->mutex);
lock(&mm->mmap_sem);
Instead of using the mmap_sem to keep mm_users constant, take the
page table spinlock.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/mm/mmu_context_hash64.c')
| -rw-r--r-- | arch/powerpc/mm/mmu_context_hash64.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/powerpc/mm/mmu_context_hash64.c b/arch/powerpc/mm/mmu_context_hash64.c index 3bafc3deca6..4ff587e3825 100644 --- a/arch/powerpc/mm/mmu_context_hash64.c +++ b/arch/powerpc/mm/mmu_context_hash64.c @@ -136,8 +136,8 @@ int use_cop(unsigned long acop, struct mm_struct *mm) if (!mm || !acop) return -EINVAL; - /* We need to make sure mm_users doesn't change */ - down_read(&mm->mmap_sem); + /* The page_table_lock ensures mm_users won't change under us */ + spin_lock(&mm->page_table_lock); spin_lock(mm->context.cop_lockp); if (mm->context.cop_pid == COP_PID_NONE) { @@ -164,7 +164,7 @@ int use_cop(unsigned long acop, struct mm_struct *mm) out: spin_unlock(mm->context.cop_lockp); - up_read(&mm->mmap_sem); + spin_unlock(&mm->page_table_lock); return ret; } @@ -185,8 +185,8 @@ void drop_cop(unsigned long acop, struct mm_struct *mm) if (WARN_ON_ONCE(!mm)) return; - /* We need to make sure mm_users doesn't change */ - down_read(&mm->mmap_sem); + /* The page_table_lock ensures mm_users won't change under us */ + spin_lock(&mm->page_table_lock); spin_lock(mm->context.cop_lockp); mm->context.acop &= ~acop; @@ -213,7 +213,7 @@ void drop_cop(unsigned long acop, struct mm_struct *mm) } spin_unlock(mm->context.cop_lockp); - up_read(&mm->mmap_sem); + spin_unlock(&mm->page_table_lock); } EXPORT_SYMBOL_GPL(drop_cop); |