linux-kernel - [RFC PATCH 5/8] ipc: shm: pass atomic parameter to do

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Message-Id: <1521581486-99134-6-git-send-email-yang.shi@linux.alibaba.com>
Date:   Wed, 21 Mar 2018 05:31:23 +0800
From:   Yang Shi <yang.shi@...ux.alibaba.com>
To:     akpm@...ux-foundation.org
Cc:     yang.shi@...ux.alibaba.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [RFC PATCH 5/8] ipc: shm: pass atomic parameter to do_munmap()

It looks safe to do unlock/relock mmap_sem in the middle of shmat(), so
passing "false" here.

Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>
---
 ipc/shm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/ipc/shm.c b/ipc/shm.c
index 4643865..1617523 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1537,7 +1537,8 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
 			 */
 			file = vma->vm_file;
 			size = i_size_read(file_inode(vma->vm_file));
-			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
+			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start,
+				  NULL, false);
 			/*
 			 * We discovered the size of the shm segment, so
 			 * break out of here and fall through to the next
@@ -1564,7 +1565,8 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
 		if ((vma->vm_ops == &shm_vm_ops) &&
 		    ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
 		    (vma->vm_file == file))
-			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
+			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start,
+				  NULL, false);
 		vma = next;
 	}
 
@@ -1573,7 +1575,8 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
 	 * given
 	 */
 	if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
-		do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
+		do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start,
+			  NULL, false);
 		retval = 0;
 	}
 
-- 
1.8.3.1