Commit 7394e76e authored Feb 09, 2015 by Tobias Lindskog Committed by Jeff Vander Stoep Jun 22, 2015

Shrink ashmem directly through shmem_fallocate



When ashmem_shrink is called from direct reclaim on a user thread, a
call to do_fallocate will check for permissions against the security
policy of that user thread.  It can thus fail by chance if called on a
thread that isn't permitted to modify the relevant ashmem areas.

Because we know that we have a shmem file underneath, call the shmem
implementation of fallocate directly instead of going through the
user-space interface for fallocate.

FIX=DMS06243560
Area: Kernel/Linux Kernel

Bug: 21951515
Change-Id: Ie98fff18a2bdeb535cd24d4fbdd13677e12681a7
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>

parent 3174b276

drivers/staging/android/ashmem.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -440,7 +440,7 @@ ashmem_shrink_scan(struct shrinker shrink, struct shrink_control sc)
		loff_t start = range->pgstart * PAGE_SIZE;
		loff_t end = (range->pgend + 1) * PAGE_SIZE;

		do_fallocate(range->asma->file,
		range->asma->file->f_op->fallocate(range->asma->file,
		FALLOC_FL_PUNCH_HOLE \| FALLOC_FL_KEEP_SIZE,
		start, end - start);
		range->purged = ASHMEM_WAS_PURGED;