linux-kernel - [PATCH v2 09/10] mmap locking API: use lockdep_assert

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Message-Id: <20200327021058.221911-10-walken@google.com>
Date:   Thu, 26 Mar 2020 19:10:57 -0700
From:   Michel Lespinasse <walken@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-mm <linux-mm@...ck.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Matthew Wilcox <willy@...radead.org>,
        Liam Howlett <Liam.Howlett@...cle.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        David Rientjes <rientjes@...gle.com>,
        Hugh Dickins <hughd@...gle.com>, Ying Han <yinghan@...gle.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Markus Elfring <Markus.Elfring@....de>,
        Michel Lespinasse <walken@...gle.com>
Subject: [PATCH v2 09/10] mmap locking API: use lockdep_assert_held

Use lockdep_assert_held when asserting that mmap_sem is held.

Using this instead of rwsem_is_locked makes the assertions more
tolerant of future changes to the lock type.

Signed-off-by: Michel Lespinasse <walken@...gle.com>
---
 fs/userfaultfd.c | 6 +++---
 mm/gup.c         | 2 +-
 mm/memory.c      | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 5914eabd8185..ad1ce223ee6a 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -234,7 +234,7 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
 	pte_t *ptep, pte;
 	bool ret = true;
 
-	VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
+	lockdep_assert_held(&mm->mmap_sem);
 
 	ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
 
@@ -286,7 +286,7 @@ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx,
 	pte_t *pte;
 	bool ret = true;
 
-	VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
+	lockdep_assert_held(&mm->mmap_sem);
 
 	pgd = pgd_offset(mm, address);
 	if (!pgd_present(*pgd))
@@ -376,7 +376,7 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason)
 	 * Coredumping runs without mmap_sem so we can only check that
 	 * the mmap_sem is held, if PF_DUMPCORE was not set.
 	 */
-	WARN_ON_ONCE(!rwsem_is_locked(&mm->mmap_sem));
+	lockdep_assert_held(&mm->mmap_sem);
 
 	ctx = vmf->vma->vm_userfaultfd_ctx.ctx;
 	if (!ctx)
diff --git a/mm/gup.c b/mm/gup.c
index d78965738e7e..1e225eba4787 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1154,7 +1154,7 @@ long populate_vma_page_range(struct vm_area_struct *vma,
 	VM_BUG_ON(end   & ~PAGE_MASK);
 	VM_BUG_ON_VMA(start < vma->vm_start, vma);
 	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
-	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+	lockdep_assert_held(&mm->mmap_sem);
 
 	gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
 	if (vma->vm_flags & VM_LOCKONFAULT)
diff --git a/mm/memory.c b/mm/memory.c
index 03fce44eee16..4c125f0a1df9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1202,7 +1202,7 @@ static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
 		next = pud_addr_end(addr, end);
 		if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
 			if (next - addr != HPAGE_PUD_SIZE) {
-				VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
+				lockdep_assert_held(&tlb->mm->mmap_sem);
 				split_huge_pud(vma, pud, addr);
 			} else if (zap_huge_pud(tlb, vma, pud, addr))
 				goto next;
-- 
2.26.0.rc2.310.g2932bb562d-goog