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mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked()

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Add new APIs to assert that mmap_sem is held.

Using this instead of rwsem_is_locked and lockdep_assert_held[_write]
makes the assertions more tolerant of future changes to the lock type.

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-10-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michel Lespinasse
2020-06-08 21:33:44 -07:00
committed by Linus Torvalds
parent 14c3656b72
commit 42fc541404
9 changed files with 28 additions and 14 deletions
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6
fs/userfaultfd.c
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@@ -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));
mmap_assert_locked(mm);
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));
mmap_assert_locked(mm);
pgd = pgd_offset(mm, address);
if (!pgd_present(*pgd))
@@ -405,7 +405,7 @@ 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));
mmap_assert_locked(mm);
ctx = vmf->vma->vm_userfaultfd_ctx.ctx;
if (!ctx)