[CRIU] [PATCHv2] pages: Share page_ids between ns dump-helpers
Dmitry Safonov
0x7f454c46 at gmail.com
Tue Aug 15 14:52:19 MSK 2017
2017-06-30 22:14 GMT+03:00 Dmitry Safonov <dsafonov at virtuozzo.com>:
> After the commit 9d2e1dfebedf ("ipc: Keep shmem segments contents into
> pagemap/page images"), SysV shmem pages are stored in the pages-<n>.img
> files. Where <n> is page_ids number.
>
> The problem here is that we dump namespaces with a helper after fork().
> This results in non-shared between child(s) and parent-criu counter
> with the result of overwriting pages-*.img files later by helpers/criu.
> This resulted in restore with corrupted shmem segments or
> in the following failures on restore:
>> (04.501019) 1: Error (criu/pagemap.c:265): Can't read mapping page 0: No such file or directory
>> (04.637516) 1: Error (criu/pagemap.c:265): Can't read mapping page 0: No such file or directory
>
> Allocate page_ids with shmalloc() and make it atomic.
> As pre-dump, dump and page-server may run as a commands during
> one service session, don't set it up early in main() - as
> on the next command the value of page_ids will be preserved.
> Rather do it lately during initialization of (pre-)dump/pageserver.
> As (pre-)dump/pageserver rpc commands are executed under fork(),
> we will not share the counter to criu.
>
> Cc: Pavel Emelyanov <xemul at virtuozzo.com>
> Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
> ---
> v2: Keep page_ids a little bit more privately by initing it later.
>
> criu/cr-dump.c | 6 ++++++
> criu/image.c | 22 +++++++++++++++++-----
> criu/include/image.h | 3 ++-
> criu/page-xfer.c | 7 ++++---
> criu/rst-malloc.c | 5 +++++
> 5 files changed, 34 insertions(+), 9 deletions(-)
ping?
>
> diff --git a/criu/cr-dump.c b/criu/cr-dump.c
> index 3f9f8d06a9ce..0ce03c601bfa 100644
> --- a/criu/cr-dump.c
> +++ b/criu/cr-dump.c
> @@ -1612,6 +1612,9 @@ int cr_pre_dump_tasks(pid_t pid)
> struct pstree_item *item;
> int ret = -1;
>
> + if (images_init(false))
> + goto err;
> +
> if (opts.remote && push_snapshot_id() < 0) {
> pr_err("Failed to push image namespace.\n");
> goto err;
> @@ -1813,6 +1816,9 @@ int cr_dump_tasks(pid_t pid)
> pr_info("Dumping processes (pid: %d)\n", pid);
> pr_info("========================================\n");
>
> + if (images_init(false))
> + goto err;
> +
> if (opts.remote && push_snapshot_id() < 0) {
> pr_err("Failed to push image namespace.\n");
> goto err;
> diff --git a/criu/image.c b/criu/image.c
> index 62e8e7109e65..4d8e9d28e8fd 100644
> --- a/criu/image.c
> +++ b/criu/image.c
> @@ -17,6 +17,7 @@
> #include "images/inventory.pb-c.h"
> #include "images/pagemap.pb-c.h"
> #include "img-remote.h"
> +#include "rst-malloc.h"
>
> bool ns_per_id = false;
> bool img_common_magic = true;
> @@ -505,10 +506,21 @@ void close_image_dir(void)
> close_service_fd(IMG_FD_OFF);
> }
>
> -static unsigned long page_ids = 1;
> +/*
> + * As we dump SysV shmem IPC into pages-<page_ids>.img,
> + * the keys should be shared in each dump ns-helpers and in criu.
> + */
> +static atomic_t *page_ids;
>
> -void up_page_ids_base(void)
> +int images_init(bool page_server_mode)
> {
> + BUG_ON(page_ids);
> + page_ids = shmalloc(sizeof(*page_ids));
> + if (!page_ids) {
> + pr_err("Failed to shmalloc page_ids\n");
> + return -1;
> + }
> +
> /*
> * When page server and criu dump work on
> * the same dir, the shmem pagemaps and regular
> @@ -516,9 +528,9 @@ void up_page_ids_base(void)
> * making page server produce page images with
> * higher IDs.
> */
> + atomic_set(page_ids, page_server_mode ? 0x10001 : 1);
>
> - BUG_ON(page_ids != 1);
> - page_ids += 0x10000;
> + return 0;
> }
>
> struct cr_img *open_pages_image_at(int dfd, unsigned long flags, struct cr_img *pmi, u32 *id)
> @@ -531,7 +543,7 @@ struct cr_img *open_pages_image_at(int dfd, unsigned long flags, struct cr_img *
> pagemap_head__free_unpacked(h, NULL);
> } else {
> PagemapHead h = PAGEMAP_HEAD__INIT;
> - *id = h.pages_id = page_ids++;
> + *id = h.pages_id = atomic_inc_return(page_ids);
> if (pb_write_one(pmi, &h, PB_PAGEMAP_HEAD) < 0)
> return NULL;
> }
> diff --git a/criu/include/image.h b/criu/include/image.h
> index d9c4bdbc8da4..705c09a424a3 100644
> --- a/criu/include/image.h
> +++ b/criu/include/image.h
> @@ -156,7 +156,6 @@ extern struct cr_img *open_image_at(int dfd, int type, unsigned long flags, ...)
> extern int open_image_lazy(struct cr_img *img);
> extern struct cr_img *open_pages_image(unsigned long flags, struct cr_img *pmi, u32 *pages_id);
> extern struct cr_img *open_pages_image_at(int dfd, unsigned long flags, struct cr_img *pmi, u32 *pages_id);
> -extern void up_page_ids_base(void);
>
> extern struct cr_img *img_from_fd(int fd); /* for cr-show mostly */
>
> @@ -170,4 +169,6 @@ extern int read_img_str(struct cr_img *, char **pstr, int size);
>
> extern void close_image(struct cr_img *);
>
> +extern int images_init(bool page_server_mode);
> +
> #endif /* __CR_IMAGE_H__ */
> diff --git a/criu/page-xfer.c b/criu/page-xfer.c
> index 52f5df9899c8..45c9bdf29f30 100644
> --- a/criu/page-xfer.c
> +++ b/criu/page-xfer.c
> @@ -923,9 +923,10 @@ int cr_page_server(bool daemon_mode, bool lazy_dump, int cfd)
> int sk = -1;
> int ret;
>
> - if (!opts.lazy_pages)
> - up_page_ids_base();
> - else if (!lazy_dump)
> + if (images_init(!opts.lazy_pages))
> + return -1;
> +
> + if (opts.lazy_pages && !lazy_dump)
> if (page_server_init_send())
> return -1;
>
> diff --git a/criu/rst-malloc.c b/criu/rst-malloc.c
> index 4f7357ca28c4..9de2fa77869b 100644
> --- a/criu/rst-malloc.c
> +++ b/criu/rst-malloc.c
> @@ -112,6 +112,11 @@ static int grow_private(struct rst_mem_type_s *t, unsigned long size)
> return grow_remap(t, MAP_PRIVATE, size);
> }
>
> +/*
> + * Service code expects that we do not share rst_mems allocator's
> + * methodata and keep it in private. Otherwise restore may leave
> + * some of shared resorces allocated to the next service command.
> + */
> static struct rst_mem_type_s rst_mems[RST_MEM_TYPES] = {
> [RM_SHARED] = {
> .grow = grow_shared,
> --
> 2.13.1
>
--
Dmitry
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