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Commit c6669c22 authored by Graf Yang's avatar Graf Yang Committed by Mike Frysinger
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Blackfin: fix up mm locking in address dumping 



The locking code in the address dumper needs to grab the mm's mmap_sem
so that other CPUs do not get an inconsistent view.  On UP systems this
really wasn't a problem, but it is easy to trigger a race on SMP systems
when another CPU removes a mapping.

Signed-off-by: default avatarGraf Yang <graf.yang@analog.com>
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
parent 7e1082b7

arch/blackfin/kernel/traps.c

+13 −1
Original line number Diff line number Diff line
@@ -138,6 +138,12 @@ static void decode_address(char *buf, unsigned long address) 
		if (!mm)

			continue;



		if (!down_read_trylock(&mm->mmap_sem)) {

			if (!in_atomic)

				mmput(mm);

			continue;

		}



		for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {

			struct vm_area_struct *vma;
@@ -177,6 +183,7 @@ static void decode_address(char *buf, unsigned long address) 
					sprintf(buf, "[ %s vma:0x%lx-0x%lx]",

						name, vma->vm_start, vma->vm_end);



				up_read(&mm->mmap_sem);

				if (!in_atomic)

					mmput(mm);
@@ -186,11 +193,16 @@ static void decode_address(char *buf, unsigned long address) 
				goto done;

			}

		}



		up_read(&mm->mmap_sem);

		if (!in_atomic)

			mmput(mm);

	}



	/* we were unable to find this address anywhere */

	/*

	 * we were unable to find this address anywhere,

	 * or some MMs were skipped because they were in use.

	 */

	sprintf(buf, "/* kernel dynamic memory */");



done: