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userfaultfd: non-cooperative: add event for exit() notification
Allow userfaultfd monitor track termination of the processes that have memory backed by the uffd. [rppt@linux.vnet.ibm.com: add comment] Link: http://lkml.kernel.org/r/20170202135448.GB19804@rapoport-lnxLink: http://lkml.kernel.org/r/1485542673-24387-4-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -774,6 +774,34 @@ void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf)
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}
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}
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void userfaultfd_exit(struct mm_struct *mm)
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{
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struct vm_area_struct *vma = mm->mmap;
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/*
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* We can do the vma walk without locking because the caller
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* (exit_mm) knows it now has exclusive access
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*/
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while (vma) {
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struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx;
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if (ctx && (ctx->features & UFFD_FEATURE_EVENT_EXIT)) {
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struct userfaultfd_wait_queue ewq;
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userfaultfd_ctx_get(ctx);
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msg_init(&ewq.msg);
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ewq.msg.event = UFFD_EVENT_EXIT;
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userfaultfd_event_wait_completion(ctx, &ewq);
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ctx->features &= ~UFFD_FEATURE_EVENT_EXIT;
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}
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vma = vma->vm_next;
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}
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}
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static int userfaultfd_release(struct inode *inode, struct file *file)
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{
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struct userfaultfd_ctx *ctx = file->private_data;
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@ -72,6 +72,8 @@ extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
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extern void userfaultfd_unmap_complete(struct mm_struct *mm,
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struct list_head *uf);
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extern void userfaultfd_exit(struct mm_struct *mm);
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#else /* CONFIG_USERFAULTFD */
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/* mm helpers */
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@ -136,6 +138,11 @@ static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
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struct list_head *uf)
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{
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}
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static inline void userfaultfd_exit(struct mm_struct *mm)
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{
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}
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#endif /* CONFIG_USERFAULTFD */
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#endif /* _LINUX_USERFAULTFD_K_H */
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@ -18,7 +18,8 @@
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* means the userland is reading).
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*/
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#define UFFD_API ((__u64)0xAA)
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#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \
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#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_EXIT | \
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UFFD_FEATURE_EVENT_FORK | \
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UFFD_FEATURE_EVENT_REMAP | \
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UFFD_FEATURE_EVENT_REMOVE | \
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UFFD_FEATURE_EVENT_UNMAP | \
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@ -112,6 +113,7 @@ struct uffd_msg {
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#define UFFD_EVENT_REMAP 0x14
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#define UFFD_EVENT_REMOVE 0x15
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#define UFFD_EVENT_UNMAP 0x16
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#define UFFD_EVENT_EXIT 0x17
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/* flags for UFFD_EVENT_PAGEFAULT */
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#define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */
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@ -161,6 +163,7 @@ struct uffdio_api {
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#define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4)
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#define UFFD_FEATURE_MISSING_SHMEM (1<<5)
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#define UFFD_FEATURE_EVENT_UNMAP (1<<6)
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#define UFFD_FEATURE_EVENT_EXIT (1<<7)
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__u64 features;
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__u64 ioctls;
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@ -45,6 +45,7 @@
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#include <linux/task_io_accounting_ops.h>
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#include <linux/tracehook.h>
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#include <linux/fs_struct.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/init_task.h>
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#include <linux/perf_event.h>
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#include <trace/events/sched.h>
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@ -547,6 +548,7 @@ static void exit_mm(void)
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enter_lazy_tlb(mm, current);
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task_unlock(current);
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mm_update_next_owner(mm);
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userfaultfd_exit(mm);
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mmput(mm);
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if (test_thread_flag(TIF_MEMDIE))
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exit_oom_victim();
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