From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Subject: userfaultfd: non-cooperative: add event for exit() notification Allow userfaultfd monitor track termination of the processes that have memory backed by the uffd. [rppt@xxxxxxxxxxxxxxxxxx: add comment] Link: http://lkml.kernel.org/r/20170202135448.GB19804@rapoport-lnxLink: http://lkml.kernel.org/r/1485542673-24387-4-git-send-email-rppt@xxxxxxxxxxxxxxxxxx Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/userfaultfd.c | 28 ++++++++++++++++++++++++++++ include/linux/userfaultfd_k.h | 7 +++++++ include/uapi/linux/userfaultfd.h | 5 ++++- kernel/exit.c | 2 ++ 4 files changed, 41 insertions(+), 1 deletion(-) diff -puN fs/userfaultfd.c~userfaultfd-non-cooperative-add-event-for-exit-notification fs/userfaultfd.c --- a/fs/userfaultfd.c~userfaultfd-non-cooperative-add-event-for-exit-notification +++ a/fs/userfaultfd.c @@ -774,6 +774,34 @@ void userfaultfd_unmap_complete(struct m } } +void userfaultfd_exit(struct mm_struct *mm) +{ + struct vm_area_struct *vma = mm->mmap; + + /* + * We can do the vma walk without locking because the caller + * (exit_mm) knows it now has exclusive access + */ + while (vma) { + struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx; + + if (ctx && (ctx->features & UFFD_FEATURE_EVENT_EXIT)) { + struct userfaultfd_wait_queue ewq; + + userfaultfd_ctx_get(ctx); + + msg_init(&ewq.msg); + ewq.msg.event = UFFD_EVENT_EXIT; + + userfaultfd_event_wait_completion(ctx, &ewq); + + ctx->features &= ~UFFD_FEATURE_EVENT_EXIT; + } + + vma = vma->vm_next; + } +} + static int userfaultfd_release(struct inode *inode, struct file *file) { struct userfaultfd_ctx *ctx = file->private_data; diff -puN include/linux/userfaultfd_k.h~userfaultfd-non-cooperative-add-event-for-exit-notification include/linux/userfaultfd_k.h --- a/include/linux/userfaultfd_k.h~userfaultfd-non-cooperative-add-event-for-exit-notification +++ a/include/linux/userfaultfd_k.h @@ -72,6 +72,8 @@ extern int userfaultfd_unmap_prep(struct extern void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf); +extern void userfaultfd_exit(struct mm_struct *mm); + #else /* CONFIG_USERFAULTFD */ /* mm helpers */ @@ -136,6 +138,11 @@ static inline void userfaultfd_unmap_com struct list_head *uf) { } + +static inline void userfaultfd_exit(struct mm_struct *mm) +{ +} + #endif /* CONFIG_USERFAULTFD */ #endif /* _LINUX_USERFAULTFD_K_H */ diff -puN include/uapi/linux/userfaultfd.h~userfaultfd-non-cooperative-add-event-for-exit-notification include/uapi/linux/userfaultfd.h --- a/include/uapi/linux/userfaultfd.h~userfaultfd-non-cooperative-add-event-for-exit-notification +++ a/include/uapi/linux/userfaultfd.h @@ -18,7 +18,8 @@ * means the userland is reading). */ #define UFFD_API ((__u64)0xAA) -#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \ +#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_EXIT | \ + UFFD_FEATURE_EVENT_FORK | \ UFFD_FEATURE_EVENT_REMAP | \ UFFD_FEATURE_EVENT_REMOVE | \ UFFD_FEATURE_EVENT_UNMAP | \ @@ -112,6 +113,7 @@ struct uffd_msg { #define UFFD_EVENT_REMAP 0x14 #define UFFD_EVENT_REMOVE 0x15 #define UFFD_EVENT_UNMAP 0x16 +#define UFFD_EVENT_EXIT 0x17 /* flags for UFFD_EVENT_PAGEFAULT */ #define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */ @@ -161,6 +163,7 @@ struct uffdio_api { #define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4) #define UFFD_FEATURE_MISSING_SHMEM (1<<5) #define UFFD_FEATURE_EVENT_UNMAP (1<<6) +#define UFFD_FEATURE_EVENT_EXIT (1<<7) __u64 features; __u64 ioctls; diff -puN kernel/exit.c~userfaultfd-non-cooperative-add-event-for-exit-notification kernel/exit.c --- a/kernel/exit.c~userfaultfd-non-cooperative-add-event-for-exit-notification +++ a/kernel/exit.c @@ -45,6 +45,7 @@ #include <linux/task_io_accounting_ops.h> #include <linux/tracehook.h> #include <linux/fs_struct.h> +#include <linux/userfaultfd_k.h> #include <linux/init_task.h> #include <linux/perf_event.h> #include <trace/events/sched.h> @@ -547,6 +548,7 @@ static void exit_mm(void) enter_lazy_tlb(mm, current); task_unlock(current); mm_update_next_owner(mm); + userfaultfd_exit(mm); mmput(mm); if (test_thread_flag(TIF_MEMDIE)) exit_oom_victim(); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
