From: Vlastimil Babka <vbabka@suse.cz>
Date: Tue, 24 Jun 2025 13:03:48 +0000 (+0200)
Subject: mm, madvise: use standard madvise locking in madvise_set_anon_name()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9992554c9ca3eb929daf8ccb02cfbcb3dbc27d4f;p=thirdparty%2Flinux.git

mm, madvise: use standard madvise locking in madvise_set_anon_name()

Use madvise_lock()/madvise_unlock() in madvise_set_anon_name() in the same
way as in do_madvise().  This narrows the lock scope a bit and reuses
existing functionality.  get_lock_mode() already picks the correct
MADVISE_MMAP_WRITE_LOCK mode for __MADV_SET_ANON_VMA_NAME so we can just
remove the explicit assignment.

There is a user visible change in that the prctl(PR_SET_VMA,
PR_SET_VMA_ANON_NAME...) might now return -EINTR.

Link: https://lkml.kernel.org/r/20250624-anon_name_cleanup-v2-4-600075462a11@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Colin Cross <ccross@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/madvise.c b/mm/madvise.c
index cb7d74d56debb..a34c2c89a53bb 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -2082,10 +2082,10 @@ static int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
 {
 	unsigned long end;
 	unsigned long len;
+	int error;
 	struct madvise_behavior madv_behavior = {
 		.mm = mm,
 		.behavior = __MADV_SET_ANON_VMA_NAME,
-		.lock_mode = MADVISE_MMAP_WRITE_LOCK,
 		.anon_name = anon_name,
 	};
 
@@ -2106,7 +2106,14 @@ static int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
 
 	madv_behavior.range.start = start;
 	madv_behavior.range.end = end;
-	return madvise_walk_vmas(&madv_behavior);
+
+	error = madvise_lock(&madv_behavior);
+	if (error)
+		return error;
+	error = madvise_walk_vmas(&madv_behavior);
+	madvise_unlock(&madv_behavior);
+
+	return error;
 }
 
 int set_anon_vma_name(unsigned long addr, unsigned long size,
@@ -2136,9 +2143,7 @@ int set_anon_vma_name(unsigned long addr, unsigned long size,
 			return -ENOMEM;
 	}
 
-	mmap_write_lock(mm);
 	error = madvise_set_anon_name(mm, addr, size, anon_name);
-	mmap_write_unlock(mm);
 	anon_vma_name_put(anon_name);
 
 	return error;