aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/kernel
diff options
context:
space:
mode:
authorDima Zavin <dima@android.com>2012-04-30 10:26:14 +0100
committerBen Hutchings <ben@decadent.org.uk>2012-05-31 00:43:49 +0100
commit6236459be5996e9417020f03ccf7019eccbf1449 (patch)
tree0837d40e85737038ab69953f89f37e4252347ad4 /arch/arm/kernel
parent5e6d6ba821e9207db88e808177ea66e8ac880983 (diff)
ARM: 7409/1: Do not call flush_cache_user_range with mmap_sem held
commit 435a7ef52db7d86e67a009b36cac1457f8972391 upstream. We can't be holding the mmap_sem while calling flush_cache_user_range because the flush can fault. If we fault on a user address, the page fault handler will try to take mmap_sem again. Since both places acquire the read lock, most of the time it succeeds. However, if another thread tries to acquire the write lock on the mmap_sem (e.g. mmap) in between the call to flush_cache_user_range and the fault, the down_read in do_page_fault will deadlock. [will: removed drop of vma parameter as already queued by rmk (7365/1)] Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Dima Zavin <dima@android.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch/arm/kernel')
-rw-r--r--arch/arm/kernel/traps.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index f363ad916ca..160cb164b2a 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -488,7 +488,9 @@ do_cache_op(unsigned long start, unsigned long end, int flags)
if (end > vma->vm_end)
end = vma->vm_end;
+ up_read(&mm->mmap_sem);
flush_cache_user_range(start, end);
+ return;
}
up_read(&mm->mmap_sem);
}