linux-kernel - [PATCH V3] mm/madvise: Move up the behavior parameter validation

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Date:   Tue, 18 Apr 2017 10:58:44 +0530
From:   Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     n-horiguchi@...jp.nec.com, akpm@...ux-foundation.org
Subject: [PATCH V3] mm/madvise: Move up the behavior parameter validation

The madvise_behavior_valid() function should be called before
acting upon the behavior parameter. Hence move up the function.
This also includes MADV_SOFT_OFFLINE and MADV_HWPOISON options
as valid behavior parameter for the system call madvise().

Signed-off-by: Anshuman Khandual <khandual@...ux.vnet.ibm.com>
---
Changes in V3:

Moved the madvise_inject_error() function down which will make
sure that the boundary conditions are checked for address and
length arguments as per Naoya.

Changes in V2:

Added CONFIG_MEMORY_FAILURE check before using MADV_SOFT_OFFLINE
and MADV_HWPOISONE constants.

 mm/madvise.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index efd4721..721dd6f 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -694,6 +694,10 @@ static int madvise_inject_error(int behavior,
 #endif
 	case MADV_DONTDUMP:
 	case MADV_DODUMP:
+#ifdef CONFIG_MEMORY_FAILURE
+	case MADV_SOFT_OFFLINE:
+	case MADV_HWPOISON:
+#endif
 		return true;
 
 	default:
@@ -767,10 +771,6 @@ static int madvise_inject_error(int behavior,
 	size_t len;
 	struct blk_plug plug;
 
-#ifdef CONFIG_MEMORY_FAILURE
-	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
-		return madvise_inject_error(behavior, start, start + len_in);
-#endif
 	if (!madvise_behavior_valid(behavior))
 		return error;
 
@@ -790,6 +790,11 @@ static int madvise_inject_error(int behavior,
 	if (end == start)
 		return error;
 
+#ifdef CONFIG_MEMORY_FAILURE
+	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
+		return madvise_inject_error(behavior, start, start + len_in);
+#endif
+
 	write = madvise_need_mmap_write(behavior);
 	if (write) {
 		if (down_write_killable(&current->mm->mmap_sem))
-- 
1.8.5.2