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authorAnton Blanchard <anton@samba.org>2011-09-14 09:43:15 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2011-11-11 09:37:11 -0800
commiteaeafcd898108e4e026faf43ca41817f5de6ee66 (patch)
tree363bec39cbe790f0aa86c657214753ad4808e270 /arch
parent71b1a9d35d6cbd2e37c1101ca5f779ca55f7fb03 (diff)
powerpc: Fix deadlock in icswx code
commit 8bdafa39a47265bc029838b35cc6585f69224afa upstream. 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> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/mm/mmu_context_hash64.c12
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 3bafc3deca6d..4ff587e38250 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);