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powerpc: Fix deadlock in icswx code

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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>
This commit is contained in:
Anton Blanchard
2011-09-14 09:43:15 +00:00
committed by Greg Kroah-Hartman
parent 71b1a9d35d
commit eaeafcd898
1 changed files with 6 additions and 6 deletions
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12
arch/powerpc/mm/mmu_context_hash64.c
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@@ -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);