From: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Subject: userfaultfd: non-cooperative: add madvise() event for MADV_DONTNEED request If the page is punched out of the address space the uffd reader should know this and zeromap the respective area in case of the #PF event. Link: http://lkml.kernel.org/r/20161216144821.5183-14-aarcange@xxxxxxxxxx Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx> Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/userfaultfd.c | 28 ++++++++++++++++++++++++++++ include/linux/userfaultfd_k.h | 12 ++++++++++++ include/uapi/linux/userfaultfd.h | 10 +++++++++- mm/madvise.c | 2 ++ 4 files changed, 51 insertions(+), 1 deletion(-) diff -puN fs/userfaultfd.c~userfaultfd-non-cooperative-add-madvise-event-for-madv_dontneed-request fs/userfaultfd.c --- a/fs/userfaultfd.c~userfaultfd-non-cooperative-add-madvise-event-for-madv_dontneed-request +++ a/fs/userfaultfd.c @@ -633,6 +633,34 @@ void mremap_userfaultfd_complete(struct userfaultfd_event_wait_completion(ctx, &ewq); } +void madvise_userfault_dontneed(struct vm_area_struct *vma, + struct vm_area_struct **prev, + unsigned long start, unsigned long end) +{ + struct mm_struct *mm = vma->vm_mm; + struct userfaultfd_ctx *ctx; + struct userfaultfd_wait_queue ewq; + + ctx = vma->vm_userfaultfd_ctx.ctx; + if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_MADVDONTNEED)) + return; + + userfaultfd_ctx_get(ctx); + up_read(&mm->mmap_sem); + + *prev = NULL; /* We wait for ACK w/o the mmap semaphore */ + + msg_init(&ewq.msg); + + ewq.msg.event = UFFD_EVENT_MADVDONTNEED; + ewq.msg.arg.madv_dn.start = start; + ewq.msg.arg.madv_dn.end = end; + + userfaultfd_event_wait_completion(ctx, &ewq); + + down_read(&mm->mmap_sem); +} + 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-madvise-event-for-madv_dontneed-request include/linux/userfaultfd_k.h --- a/include/linux/userfaultfd_k.h~userfaultfd-non-cooperative-add-madvise-event-for-madv_dontneed-request +++ a/include/linux/userfaultfd_k.h @@ -61,6 +61,11 @@ extern void mremap_userfaultfd_complete( unsigned long from, unsigned long to, unsigned long len); +extern void madvise_userfault_dontneed(struct vm_area_struct *vma, + struct vm_area_struct **prev, + unsigned long start, + unsigned long end); + #else /* CONFIG_USERFAULTFD */ /* mm helpers */ @@ -106,6 +111,13 @@ static inline void mremap_userfaultfd_co unsigned long len) { } + +static inline void madvise_userfault_dontneed(struct vm_area_struct *vma, + struct vm_area_struct **prev, + unsigned long start, + unsigned long end) +{ +} #endif /* CONFIG_USERFAULTFD */ #endif /* _LINUX_USERFAULTFD_K_H */ diff -puN include/uapi/linux/userfaultfd.h~userfaultfd-non-cooperative-add-madvise-event-for-madv_dontneed-request include/uapi/linux/userfaultfd.h --- a/include/uapi/linux/userfaultfd.h~userfaultfd-non-cooperative-add-madvise-event-for-madv_dontneed-request +++ a/include/uapi/linux/userfaultfd.h @@ -19,7 +19,8 @@ */ #define UFFD_API ((__u64)0xAA) #define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \ - UFFD_FEATURE_EVENT_REMAP) + UFFD_FEATURE_EVENT_REMAP | \ + UFFD_FEATURE_EVENT_MADVDONTNEED) #define UFFD_API_IOCTLS \ ((__u64)1 << _UFFDIO_REGISTER | \ (__u64)1 << _UFFDIO_UNREGISTER | \ @@ -84,6 +85,11 @@ struct uffd_msg { } remap; struct { + __u64 start; + __u64 end; + } madv_dn; + + struct { /* unused reserved fields */ __u64 reserved1; __u64 reserved2; @@ -98,6 +104,7 @@ struct uffd_msg { #define UFFD_EVENT_PAGEFAULT 0x12 #define UFFD_EVENT_FORK 0x13 #define UFFD_EVENT_REMAP 0x14 +#define UFFD_EVENT_MADVDONTNEED 0x15 /* flags for UFFD_EVENT_PAGEFAULT */ #define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */ @@ -119,6 +126,7 @@ struct uffdio_api { #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0) #define UFFD_FEATURE_EVENT_FORK (1<<1) #define UFFD_FEATURE_EVENT_REMAP (1<<2) +#define UFFD_FEATURE_EVENT_MADVDONTNEED (1<<3) __u64 features; __u64 ioctls; diff -puN mm/madvise.c~userfaultfd-non-cooperative-add-madvise-event-for-madv_dontneed-request mm/madvise.c --- a/mm/madvise.c~userfaultfd-non-cooperative-add-madvise-event-for-madv_dontneed-request +++ a/mm/madvise.c @@ -10,6 +10,7 @@ #include <linux/syscalls.h> #include <linux/mempolicy.h> #include <linux/page-isolation.h> +#include <linux/userfaultfd_k.h> #include <linux/hugetlb.h> #include <linux/falloc.h> #include <linux/sched.h> @@ -477,6 +478,7 @@ static long madvise_dontneed(struct vm_a return -EINVAL; zap_page_range(vma, start, end - start, NULL); + madvise_userfault_dontneed(vma, prev, start, end); return 0; } _ -- 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
