From: Jay Cornwall <jay.cornwall@amd.com>
Date: Mon, 28 Apr 2014 22:27:46 +0000 (-0500)
Subject: iommu/amd: Take mmap_sem when calling get_user_pages
X-Git-Tag: firefly_0821_release~176^2~3887^2~1
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4378d99295fae5fd42b0ed1a3eeef2a1684e0c17;p=firefly-linux-kernel-4.4.55.git

iommu/amd: Take mmap_sem when calling get_user_pages

get_user_pages requires caller to hold a read lock on mmap_sem.

Signed-off-by: Jay Cornwall <jay.cornwall@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>
---

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index 5208828792e6..203b2e6a91cf 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -504,8 +504,10 @@ static void do_fault(struct work_struct *work)
 
 	write = !!(fault->flags & PPR_FAULT_WRITE);
 
+	down_read(&fault->state->mm->mmap_sem);
 	npages = get_user_pages(fault->state->task, fault->state->mm,
 				fault->address, 1, write, 0, &page, NULL);
+	up_read(&fault->state->mm->mmap_sem);
 
 	if (npages == 1) {
 		put_page(page);