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

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>

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index ea2a3d151294abff2646344f5feddf5f77765d5e..081cdfdf11f455d60f6d8f973f1e0b4ad1787b0f 100644 (file)
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2181,7 +2181,7 @@ static void x86_pmu_event_mapped(struct perf_event *event, struct mm_struct *mm)
         * For now, this can't happen because all callers hold mmap_sem
         * for write.  If this changes, we'll need a different solution.
         */
-       lockdep_assert_held_write(&mm->mmap_sem);
+       mmap_assert_write_locked(mm);
 
        if (atomic_inc_return(&mm->context.perf_rdpmc_allowed) == 1)
                on_each_cpu_mask(mm_cpumask(mm), cr4_update_pce, NULL, 1);

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 9c645eee1a59503f16acff6fffa04255e863aeff..12b4924090406af1bb0b252c0e72e0b784df5cf8 100644 (file)
--- 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));
+       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)

diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index acac1bf5ecd20260057c664df989a627e4185d8d..43ef914e6468dfcecade2e10d317efa7e0f85e01 100644 (file)
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -1,6 +1,8 @@
 #ifndef _LINUX_MMAP_LOCK_H
 #define _LINUX_MMAP_LOCK_H
 
+#include <linux/mmdebug.h>
+
 #define MMAP_LOCK_INITIALIZER(name) \
        .mmap_sem = __RWSEM_INITIALIZER((name).mmap_sem),
 
@@ -73,4 +75,16 @@ static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
        up_read_non_owner(&mm->mmap_sem);
 }
 
+static inline void mmap_assert_locked(struct mm_struct *mm)
+{
+       lockdep_assert_held(&mm->mmap_sem);
+       VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+}
+
+static inline void mmap_assert_write_locked(struct mm_struct *mm)
+{
+       lockdep_assert_held_write(&mm->mmap_sem);
+       VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+}
+
 #endif /* _LINUX_MMAP_LOCK_H */

diff --git a/mm/gup.c b/mm/gup.c
index 41c648947fbef92c6cf475d752f5dabdb0015936..279739fbd09aaa5495861d24bece16547660d8c1 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1425,7 +1425,7 @@ 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);
+       mmap_assert_locked(mm);
 
        gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
        if (vma->vm_flags & VM_LOCKONFAULT)

diff --git a/mm/hmm.c b/mm/hmm.c
index 41673a6d8d46d1fbf5da3863aba8923745805e5e..e9a545751108cd165dd61a4c67589967bf9e8602 100644 (file)
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -563,7 +563,7 @@ int hmm_range_fault(struct hmm_range *range)
        struct mm_struct *mm = range->notifier->mm;
        int ret;
 
-       lockdep_assert_held(&mm->mmap_sem);
+       mmap_assert_locked(mm);
 
        do {
                /* If range is no longer valid force retry. */

diff --git a/mm/memory.c b/mm/memory.c
index 4615d321d77b4aee59cb5fe8e5171d5957978735..533293faaaf552934ba06f4e88393d4a1ad18d57 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1211,7 +1211,7 @@ 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);
+                               mmap_assert_locked(tlb->mm);
                                split_huge_pud(vma, pud, addr);
                        } else if (zap_huge_pud(tlb, vma, pud, addr))
                                goto next;

diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index cfd0a03bf5cccda7f9f6bbf29e02a1786d79f9f5..24eb9d1ed0a73da14e192500eda8048f1d5ce27d 100644 (file)
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -609,7 +609,7 @@ int __mmu_notifier_register(struct mmu_notifier *subscription,
        struct mmu_notifier_subscriptions *subscriptions = NULL;
        int ret;
 
-       lockdep_assert_held_write(&mm->mmap_sem);
+       mmap_assert_write_locked(mm);
        BUG_ON(atomic_read(&mm->mm_users) <= 0);
 
        if (IS_ENABLED(CONFIG_LOCKDEP)) {
@@ -761,7 +761,7 @@ struct mmu_notifier *mmu_notifier_get_locked(const struct mmu_notifier_ops *ops,
        struct mmu_notifier *subscription;
        int ret;
 
-       lockdep_assert_held_write(&mm->mmap_sem);
+       mmap_assert_write_locked(mm);
 
        if (mm->notifier_subscriptions) {
                subscription = find_get_mmu_notifier(mm, ops);
@@ -1006,7 +1006,7 @@ int mmu_interval_notifier_insert_locked(
                mm->notifier_subscriptions;
        int ret;
 
-       lockdep_assert_held_write(&mm->mmap_sem);
+       mmap_assert_write_locked(mm);
 
        if (!subscriptions || !subscriptions->has_itree) {
                ret = __mmu_notifier_register(NULL, mm);

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 928df1638c30d124d500dfa024a7ba61c1b9d4bf..3b452aa05cd08c10490d49a0887702fc4d520a00 100644 (file)
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -395,7 +395,7 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
        if (!walk.mm)
                return -EINVAL;
 
-       lockdep_assert_held(&walk.mm->mmap_sem);
+       mmap_assert_locked(walk.mm);
 
        vma = find_vma(walk.mm, start);
        do {
@@ -453,7 +453,7 @@ int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
        if (start >= end || !walk.mm)
                return -EINVAL;
 
-       lockdep_assert_held(&walk.mm->mmap_sem);
+       mmap_assert_locked(walk.mm);
 
        return __walk_page_range(start, end, &walk);
 }
@@ -472,7 +472,7 @@ int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
        if (!walk.mm)
                return -EINVAL;
 
-       lockdep_assert_held(&walk.mm->mmap_sem);
+       mmap_assert_locked(walk.mm);
 
        err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
        if (err > 0)

diff --git a/mm/util.c b/mm/util.c
index e7e8647fa205e2eeaaef3fb9c80c224106aa9e14..09f62d7d6e3e692d248a32b89ccbe31feef9158d 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -437,7 +437,7 @@ int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
        unsigned long locked_vm, limit;
        int ret = 0;
 
-       lockdep_assert_held_write(&mm->mmap_sem);
+       mmap_assert_write_locked(mm);
 
        locked_vm = mm->locked_vm;
        if (inc) {