[CRIU] [PATCH] Punch holes in input files when restoring anonymous non-shared memory
Andrei Vagin
avagin at virtuozzo.com
Wed Jul 25 03:11:13 MSK 2018
On Tue, Jul 17, 2018 at 03:38:57PM +0200, Pawel Stradomski wrote:
> Punch holes in input files when restoring anonymous non-shared memory
> if --auto-dedup is enabled.
We need to update the description for --auto-dedup and describe this new
behaviour there.
With these changes, criu restore can be executed only once. I think we
need to do something, so that a second attempt of restoring from these
images fails with a error.
We need to think how to test this functionality.
>
> This reduces memory usage if image files are stored on tmpfs.
>
> Signed-off-by: Pawel Stradomski <pstradomski at google.com>
>
> ---
> compel/arch/arm/plugins/std/syscalls/syscall.def | 1 +
> .../ppc64/plugins/std/syscalls/syscall-ppc64.tbl | 1 +
> .../s390/plugins/std/syscalls/syscall-s390.tbl | 1 +
> .../arch/x86/plugins/std/syscalls/syscall_32.tbl | 1 +
> .../arch/x86/plugins/std/syscalls/syscall_64.tbl | 1 +
> criu/mem.c | 3 ++-
> criu/pie/restorer.c | 16 ++++++++++++++++
> 7 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/compel/arch/arm/plugins/std/syscalls/syscall.def b/compel/arch/arm/plugins/std/syscalls/syscall.def
> index b68f9f2f..bcd61d4a 100644
> --- a/compel/arch/arm/plugins/std/syscalls/syscall.def
> +++ b/compel/arch/arm/plugins/std/syscalls/syscall.def
> @@ -109,3 +109,4 @@ seccomp 277 383 (unsigned int op, unsigned int flags, const char *uargs)
> gettimeofday 169 78 (struct timeval *tv, struct timezone *tz)
> preadv_raw 69 361 (int fd, struct iovec *iov, unsigned long nr, unsigned long pos_l, unsigned long pos_h)
> userfaultfd 282 388 (int flags)
> +fallocate 47 352 (int fd, int mode, loff_t offset, loff_t len)
> diff --git a/compel/arch/ppc64/plugins/std/syscalls/syscall-ppc64.tbl b/compel/arch/ppc64/plugins/std/syscalls/syscall-ppc64.tbl
> index fa0b034e..62e0bc1a 100644
> --- a/compel/arch/ppc64/plugins/std/syscalls/syscall-ppc64.tbl
> +++ b/compel/arch/ppc64/plugins/std/syscalls/syscall-ppc64.tbl
> @@ -89,6 +89,7 @@ __NR_set_robust_list 300 sys_set_robust_list (struct robust_list_head *head, si
> __NR_get_robust_list 299 sys_get_robust_list (int pid, struct robust_list_head **head_ptr, size_t *len_ptr)
> __NR_vmsplice 285 sys_vmsplice (int fd, const struct iovec *iov, unsigned long nr_segs, unsigned int flags)
> __NR_openat 286 sys_openat (int dfd, const char *filename, int flags, int mode)
> +__NR_fallocate 309 sys_fallocate (int fd, int mode, loff_t offset, loff_t len)
> __NR_timerfd_settime 311 sys_timerfd_settime (int ufd, int flags, const struct itimerspec *utmr, struct itimerspec *otmr)
> __NR_signalfd4 313 sys_signalfd (int fd, k_rtsigset_t *mask, size_t sizemask, int flags)
> __NR_rt_tgsigqueueinfo 322 sys_rt_tgsigqueueinfo (pid_t tgid, pid_t pid, int sig, siginfo_t *info)
> diff --git a/compel/arch/s390/plugins/std/syscalls/syscall-s390.tbl b/compel/arch/s390/plugins/std/syscalls/syscall-s390.tbl
> index bc77ae97..3521e915 100644
> --- a/compel/arch/s390/plugins/std/syscalls/syscall-s390.tbl
> +++ b/compel/arch/s390/plugins/std/syscalls/syscall-s390.tbl
> @@ -89,6 +89,7 @@ __NR_set_robust_list 304 sys_set_robust_list (struct robust_list_head *head, si
> __NR_get_robust_list 305 sys_get_robust_list (int pid, struct robust_list_head **head_ptr, size_t *len_ptr)
> __NR_vmsplice 309 sys_vmsplice (int fd, const struct iovec *iov, unsigned long nr_segs, unsigned int flags)
> __NR_openat 288 sys_openat (int dfd, const char *filename, int flags, int mode)
> +__NR_fallocate 314 sys_fallocate (int fd, int mode, loff_t offset, loff_t len)
> __NR_timerfd_settime 320 sys_timerfd_settime (int ufd, int flags, const struct itimerspec *utmr, struct itimerspec *otmr)
> __NR_signalfd4 322 sys_signalfd (int fd, k_rtsigset_t *mask, size_t sizemask, int flags)
> __NR_rt_tgsigqueueinfo 330 sys_rt_tgsigqueueinfo (pid_t tgid, pid_t pid, int sig, siginfo_t *info)
> diff --git a/compel/arch/x86/plugins/std/syscalls/syscall_32.tbl b/compel/arch/x86/plugins/std/syscalls/syscall_32.tbl
> index 9e1de281..a6c55b83 100644
> --- a/compel/arch/x86/plugins/std/syscalls/syscall_32.tbl
> +++ b/compel/arch/x86/plugins/std/syscalls/syscall_32.tbl
> @@ -83,6 +83,7 @@ __NR_set_robust_list 311 sys_set_robust_list (struct robust_list_head *head, si
> __NR_get_robust_list 312 sys_get_robust_list (int pid, struct robust_list_head **head_ptr, size_t *len_ptr)
> __NR_vmsplice 316 sys_vmsplice (int fd, const struct iovec *iov, unsigned int nr_segs, unsigned int flags)
> __NR_signalfd 321 sys_signalfd (int ufd, const k_rtsigset_t *sigmask, size_t sigsetsize)
> +__NR_fallocate 324 sys_fallocate (int fd, int mode, loff_t offset, loff_t len)
> __NR_timerfd_settime 325 sys_timerfd_settime (int ufd, int flags, const struct itimerspec *utmr, struct itimerspec *otmr)
> __NR_preadv 333 sys_preadv_raw (int fd, struct iovec *iov, unsigned long nr, unsigned long pos_l, unsigned long pos_h)
> __NR_rt_tgsigqueueinfo 335 sys_rt_tgsigqueueinfo (pid_t tgid, pid_t pid, int sig, siginfo_t *uinfo)
> diff --git a/compel/arch/x86/plugins/std/syscalls/syscall_64.tbl b/compel/arch/x86/plugins/std/syscalls/syscall_64.tbl
> index 726fa797..64271514 100644
> --- a/compel/arch/x86/plugins/std/syscalls/syscall_64.tbl
> +++ b/compel/arch/x86/plugins/std/syscalls/syscall_64.tbl
> @@ -94,6 +94,7 @@ __NR_set_robust_list 273 sys_set_robust_list (struct robust_list_head *head, s
> __NR_get_robust_list 274 sys_get_robust_list (int pid, struct robust_list_head **head_ptr, size_t *len_ptr)
> __NR_seccomp 317 sys_seccomp (unsigned int op, unsigned int flags, const char *uargs)
> __NR_vmsplice 278 sys_vmsplice (int fd, const struct iovec *iov, unsigned long nr_segs, unsigned int flags)
> +__NR_fallocate 285 sys_fallocate (int fd, int mode, loff_t offset, loff_t len)
> __NR_timerfd_settime 286 sys_timerfd_settime (int ufd, int flags, const struct itimerspec *utmr, struct itimerspec *otmr)
> __NR_signalfd4 289 sys_signalfd (int fd, k_rtsigset_t *mask, size_t sizemask, int flags)
> __NR_preadv 295 sys_preadv_raw (int fd, struct iovec *iov, unsigned long nr, unsigned long pos_l, unsigned long pos_h)
> diff --git a/criu/mem.c b/criu/mem.c
> index d020b7fd..c3d604a5 100644
> --- a/criu/mem.c
> +++ b/criu/mem.c
> @@ -1271,7 +1271,8 @@ static int prepare_vma_ios(struct pstree_item *t, struct task_restore_args *ta)
> {
> struct cr_img *pages;
>
> - pages = open_image(CR_FD_PAGES, O_RSTR, rsti(t)->pages_img_id);
> + pages = open_image(CR_FD_PAGES, opts.auto_dedup ? O_RDWR : O_RSTR,
> + rsti(t)->pages_img_id);
Could you add a comment here which explain why O_RDWR is required?
> if (!pages)
> return -1;
>
> diff --git a/criu/pie/restorer.c b/criu/pie/restorer.c
> index f990e9b7..3f1a8a6b 100644
> --- a/criu/pie/restorer.c
> +++ b/criu/pie/restorer.c
> @@ -646,6 +646,15 @@ static unsigned long restore_mapping(VmaEntry *vma_entry)
> !(vma_entry->status & VMA_NO_PROT_WRITE))
> prot |= PROT_WRITE;
>
> + /* TODO: if the mapping had MAP_LOCKED bit set, then the mmap will
> + * cause immediate page-in and increase in process memory usage,
> + * thus defeating attempts to conserve memory by running fallocate after
> + * each preadv.
> + *
> + * This could be fixed by zeroing MAP_LOCKED bit here and restoring it
> + * after all the contents is already loaded and the tmpfs files released
> + * by fallocate.
Unfortunately, I don't understand this comment. Maybe you can elaborate
with more details.
> + */
> pr_debug("\tmmap(%"PRIx64" -> %"PRIx64", %x %x %d)\n",
> vma_entry->start, vma_entry->end,
> prot, flags, (int)vma_entry->fd);
There is one more place where a private memory is restored. It is in
restore_priv_vma_content(). Do we want to do the same for shared memory?
> @@ -1367,6 +1376,13 @@ long __export_restore_task(struct task_restore_args *args)
> }
>
> pr_debug("`- returned %ld\n", (long)r);
> + /* TODO: Check if auto-dedup is enabled instead of trusting fallocate to fail
> + * if the file is not opened for writing. */
> + if (r > 0) {
> + pr_debug(" `fallocate %d %ld %ld\n", args->vma_ios_fd, rio->off, r);
> + sys_fallocate(args->vma_ios_fd, FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE,
> + rio->off, r);
We have to check a return code and print an error.
> + }
> rio->off += r;
> /* Advance the iovecs */
> do {
> --
> 2.18.0.203.gfac676dfb9-goog
>
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