[CRIU] [PATCH v2 7/7] lazy-pages: allow handling multiple processes
Andrew Vagin
avagin at virtuozzo.com
Wed Jun 15 21:45:09 PDT 2016
On Mon, Apr 18, 2016 at 04:34:38PM +0300, Mike Rapoport wrote:
> Signed-off-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
> ---
> criu/uffd.c | 157 ++++++++++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 116 insertions(+), 41 deletions(-)
>
> diff --git a/criu/uffd.c b/criu/uffd.c
> index 652efa4..15cfa56 100644
> --- a/criu/uffd.c
> +++ b/criu/uffd.c
> @@ -43,8 +43,69 @@ struct lazy_pages_info {
>
> unsigned long total_pages;
> unsigned long copied_pages;
> +
> + struct hlist_node hash;
> };
>
> +#define LPI_HASH_SIZE 16
> +static struct hlist_head lpi_hash[LPI_HASH_SIZE];
> +
> +static struct lazy_pages_info *lpi_init(void)
> +{
> + struct lazy_pages_info *lpi = NULL;
> +
> + lpi = malloc(sizeof(*lpi));
> + if (!lpi) {
> + pr_err("allocation failed\n");
> + return NULL;
> + }
> +
> + memset(lpi, 0, sizeof(*lpi));
> + INIT_LIST_HEAD(&lpi->pages);
> + INIT_HLIST_NODE(&lpi->hash);
> +
> + return lpi;
> +}
> +
> +static void lpi_fini(struct lazy_pages_info *lpi)
> +{
> + if (lpi->uffd)
> + close(lpi->uffd);
> + free(lpi);
> +}
> +
> +static void lpi_hash_init(void)
> +{
> + int i;
> +
> + for (i = 0; i < LPI_HASH_SIZE; i++)
> + INIT_HLIST_HEAD(&lpi_hash[i]);
> +}
> +
> +struct lazy_pages_info *uffd_to_lpi(int uffd)
> +{
> + struct lazy_pages_info *lpi;
> + struct hlist_head *head;
> +
> + head = &lpi_hash[uffd % LPI_HASH_SIZE];
> + hlist_for_each_entry(lpi, head, hash)
> + if (lpi->uffd == uffd)
> + return lpi;
> +
> + return NULL;
> +}
> +
> +static void lpi_hash_fini(void)
> +{
> + struct lazy_pages_info *p;
> + struct hlist_node *n;
> + int i;
> +
> + for (i = 0; i < LPI_HASH_SIZE; i++)
> + hlist_for_each_entry_safe(p, n, &lpi_hash[i], hash)
> + lpi_fini(p);
> +}
> +
> static int send_uffd(int sendfd, int pid)
> {
> int fd;
> @@ -165,33 +226,33 @@ out:
>
> static int find_vmas(struct lazy_pages_info *lpi);
>
> -static int ud_open(struct lazy_pages_info *lpi, int listen,
> - struct sockaddr_un *saddr)
> +static struct lazy_pages_info *ud_open(int listen, struct sockaddr_un *saddr)
> {
> + struct lazy_pages_info *lpi;
> int client;
> int ret = -1;
> socklen_t len;
> int uffd_flags;
>
> - memset(lpi, 0, sizeof(*lpi));
> - INIT_LIST_HEAD(&lpi->pages);
> -
> /* accept new client request */
> len = sizeof(struct sockaddr_un);
> if ((client = accept(listen, saddr, &len)) < 0) {
> pr_perror("server_accept error: %d", client);
> close(listen);
> - return -1;
> + return NULL;
> }
>
> pr_debug("client fd %d\n", client);
>
> + lpi = lpi_init();
> + if (!lpi)
> + goto out;
> +
> /* The "transfer protocol" is first the pid as int and then
> * the FD for UFFD */
> ret = recv(client, &lpi->pid, sizeof(lpi->pid), 0);
> if (ret != sizeof(lpi->pid)) {
> pr_perror("PID recv error:");
> - ret = -1;
> goto out;
> }
> pr_debug("received PID: %d\n", lpi->pid);
> @@ -199,7 +260,6 @@ static int ud_open(struct lazy_pages_info *lpi, int listen,
> lpi->uffd = recv_fd(client);
> if (lpi->uffd < 0) {
> pr_perror("recv_fd error:");
> - ret = -1;
> goto out;
> }
> pr_debug("lpi->uffd %d\n", lpi->uffd);
> @@ -214,11 +274,16 @@ static int ud_open(struct lazy_pages_info *lpi, int listen,
> * so that it is trackable when all pages have been transferred.
> */
> if ((lpi->total_pages = find_vmas(lpi)) == -1)
> - return -1;
> + goto out;
> +
> + hlist_add_head(&lpi->hash, &lpi_hash[lpi->uffd % LPI_HASH_SIZE]);
> +
> + return lpi;
>
> out:
> + free(lpi);
> close(client);
> - return ret;
> + return NULL;
> }
>
> static int get_page(struct lazy_pages_info *lpi, unsigned long addr, void *dest)
> @@ -581,7 +646,8 @@ static int handle_user_fault(struct lazy_pages_info *lpi, void *dest)
>
> static int lazy_pages_summary(struct lazy_pages_info *lpi)
> {
> - pr_debug("With UFFD transferred pages: (%ld/%ld)\n", lpi->copied_pages, lpi->total_pages);
> + pr_debug("Process %d: with UFFD transferred pages: (%ld/%ld)\n",
> + lpi->pid, lpi->copied_pages, lpi->total_pages);
>
> if ((lpi->copied_pages != lpi->total_pages) && (lpi->total_pages > 0)) {
> pr_warn("Only %ld of %ld pages transferred via UFFD\n", lpi->copied_pages,
> @@ -595,13 +661,14 @@ static int lazy_pages_summary(struct lazy_pages_info *lpi)
>
> #define POLL_TIMEOUT 5000
>
> -static int handle_requests(struct lazy_pages_info *lpi, int epollfd,
> - struct epoll_event *events)
> +static int handle_requests(int epollfd, struct epoll_event *events)
> {
> int nr_fds = task_entries->nr_tasks;
> + struct lazy_pages_info *lpi;
> int ret = -1;
> unsigned long ps;
> void *dest;
> + int i;
>
> /* All operations will be done on page size */
> ps = page_size();
> @@ -624,23 +691,31 @@ static int handle_requests(struct lazy_pages_info *lpi, int epollfd,
> break;
> }
>
> - ret = handle_user_fault(lpi, dest);
> - if (ret < 0)
> - goto out;
> + for (i = 0; i < ret; i++) {
> + lpi = uffd_to_lpi(events[i].data.fd);
CID 163485 (#2 of 2): Dereference null return value (NULL_RETURNS)
7. dereference: Dereferencing a pointer that might be null dest when
calling handle_user_fault. [show details]
if (lpi == NULL)
goto somewere;
> + ret = handle_user_fault(lpi, dest);
ret is used in for()
> + if (ret < 0)
> + goto out;
> + }
> }
> pr_debug("Handle remaining pages\n");
> - ret = handle_remaining_pages(lpi, dest);
> - if (ret < 0) {
> - pr_err("Error during remaining page copy\n");
> - ret = 1;
> - goto out;
> + for (i = 0; i < LPI_HASH_SIZE; i++) {
> + hlist_for_each_entry(lpi, &lpi_hash[i], hash) {
> + ret = handle_remaining_pages(lpi, dest);
> + if (ret < 0) {
> + pr_err("Error during remaining page copy\n");
> + ret = 1;
> + goto out;
> + }
> + }
> }
>
> - ret = lazy_pages_summary(lpi);
> + for (i = 0; i < LPI_HASH_SIZE; i++)
> + hlist_for_each_entry(lpi, &lpi_hash[i], hash)
> + ret += lazy_pages_summary(lpi);
>
> out:
> free(dest);
> - close(lpi->uffd);
> return ret;
>
> }
> @@ -657,12 +732,6 @@ static int lazy_pages_prepare_pstree(void)
> if (prepare_pstree() == -1)
> return -1;
>
> - /* bail out early until we know how to handle multiple tasks */
> - if (task_entries->nr_tasks > 1) {
> - pr_msg("lazy-pages cannot restore more than one task, sorry\n");
> - return -1;
> - }
> -
> return 0;
> }
>
> @@ -703,8 +772,9 @@ static int epoll_add_fd(int epollfd, int fd)
> return 0;
> }
>
> -static int prepare_uffds(struct lazy_pages_info *lpi, int epollfd)
> +static int prepare_uffds(int epollfd)
> {
> + int i;
> int listen;
> struct sockaddr_un saddr;
>
> @@ -714,29 +784,29 @@ static int prepare_uffds(struct lazy_pages_info *lpi, int epollfd)
> return -1;
> }
>
> - if (ud_open(lpi, listen, &saddr) < 0) {
> - pr_perror("uffd open error");
> - goto close_unix_sock;
> + for (i = 0; i < task_entries->nr_tasks; i++) {
> + struct lazy_pages_info *lpi;
> + lpi = ud_open(listen, &saddr);
> + if (!lpi)
> + goto close_uffd;
> + if (epoll_add_fd(epollfd, lpi->uffd))
> + goto close_uffd;
> }
>
> - if (epoll_add_fd(epollfd, lpi->uffd))
> - goto close_uffd;
> -
> close(listen);
> return 0;
>
> close_uffd:
> - close(lpi->uffd);
> -close_unix_sock:
> + lpi_hash_fini();
> close(listen);
> return -1;
> }
>
> int cr_lazy_pages()
> {
> - struct lazy_pages_info lpi;
> struct epoll_event *events;
> int epollfd;
> + int ret;
>
> if (!opts.addr) {
> pr_info("Please specify a file name for the unix domain socket\n");
> @@ -746,6 +816,8 @@ int cr_lazy_pages()
> return -1;
> }
>
> + lpi_hash_init();
> +
> if (lazy_pages_prepare_pstree())
> return -1;
>
> @@ -753,10 +825,13 @@ int cr_lazy_pages()
> if (epollfd < 0)
> return -1;
>
> - if (prepare_uffds(&lpi, epollfd))
> + if (prepare_uffds(epollfd))
> return -1;
>
> - return handle_requests(&lpi, epollfd, events);
> + ret = handle_requests(epollfd, events);
> + lpi_hash_fini();
> +
> + return ret;
> }
>
> #else /* CONFIG_HAS_UFFD */
> --
> 1.9.1
>
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