From: Manas <manas18244@iiitd.ac.in>
Date: Fri, 4 Oct 2024 17:42:16 +0000 (+0530)
Subject: mm/memory.c: simplify pfnmap_lockdep_assert
X-Git-Tag: v6.13-rc1~99^2~111
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=722376934b6c0b8692f32784d7755bbe5be67529;p=thirdparty%2Flinux.git

mm/memory.c: simplify pfnmap_lockdep_assert

Use local `mapping' to reduce the pointer chasing.

akpm: extracted from a bugfix which Linus fixed with b1b46751671be ("mm:
fix follow_pfnmap API lockdep assert").

Link: https://lkml.kernel.org/r/20241004-fix-null-deref-v4-1-d0a8ec01ac85@iiitd.ac.in
Signed-off-by: Manas <manas18244@iiitd.ac.in>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Anup Sharma <anupnewsmail@gmail.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/memory.c b/mm/memory.c
index 68e57b33363b4..2d32023d4eb87 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6388,7 +6388,7 @@ static inline void pfnmap_lockdep_assert(struct vm_area_struct *vma)
 	struct address_space *mapping = file ? file->f_mapping : NULL;
 
 	if (mapping)
-		lockdep_assert(lockdep_is_held(&vma->vm_file->f_mapping->i_mmap_rwsem) ||
+		lockdep_assert(lockdep_is_held(&mapping->i_mmap_rwsem) ||
 			       lockdep_is_held(&vma->vm_mm->mmap_lock));
 	else
 		lockdep_assert(lockdep_is_held(&vma->vm_mm->mmap_lock));