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-rw-r--r--mm/memory.c24
1 files changed, 17 insertions, 7 deletions
diff --git a/mm/memory.c b/mm/memory.c
index c48f8df6e502..4a42a74a2240 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1171,6 +1171,15 @@ copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
0, src_vma, src_mm, addr, end);
mmu_notifier_invalidate_range_start(&range);
+ /*
+ * Disabling preemption is not needed for the write side, as
+ * the read side doesn't spin, but goes to the mmap_lock.
+ *
+ * Use the raw variant of the seqcount_t write API to avoid
+ * lockdep complaining about preemptibility.
+ */
+ mmap_assert_write_locked(src_mm);
+ raw_write_seqcount_begin(&src_mm->write_protect_seq);
}
ret = 0;
@@ -1187,8 +1196,10 @@ copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
}
} while (dst_pgd++, src_pgd++, addr = next, addr != end);
- if (is_cow)
+ if (is_cow) {
+ raw_write_seqcount_end(&src_mm->write_protect_seq);
mmu_notifier_invalidate_range_end(&range);
+ }
return ret;
}
@@ -4874,11 +4885,10 @@ EXPORT_SYMBOL_GPL(generic_access_phys);
#endif
/*
- * Access another process' address space as given in mm. If non-NULL, use the
- * given task for page fault accounting.
+ * Access another process' address space as given in mm.
*/
-int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
- unsigned long addr, void *buf, int len, unsigned int gup_flags)
+int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
+ int len, unsigned int gup_flags)
{
struct vm_area_struct *vma;
void *old_buf = buf;
@@ -4955,7 +4965,7 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
void *buf, int len, unsigned int gup_flags)
{
- return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
+ return __access_remote_vm(mm, addr, buf, len, gup_flags);
}
/*
@@ -4973,7 +4983,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr,
if (!mm)
return 0;
- ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
+ ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
mmput(mm);