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https://github.com/checkpoint-restore/criu.git
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dump: Snapshot memory
It's quite simple -- get parent's pagemap before dumping memory, then collect _full_ pagemap of task putting holes into page-pipe when the page is (soft-dirty-clear && in-parent-map). At the end reset task's soft-dirty bits. This requires kernel support from http://comments.gmane.org/gmane.linux.kernel.mm/98283 Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Pavel Emelyanov
parent
60fc6abfd7
commit
433c46625e
2 changed files with 184 additions and 5 deletions
187
mem.c
187
mem.c
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@ -1,6 +1,7 @@
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#include <unistd.h>
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#include <stdio.h>
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#include <sys/mman.h>
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#include <errno.h>
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#include "crtools.h"
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#include "mem.h"
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@ -10,9 +11,128 @@
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#include "page-xfer.h"
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#include "log.h"
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#include "protobuf.h"
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#include "protobuf/pagemap.pb-c.h"
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#define PME_PRESENT (1ULL << 63)
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#define PME_SWAP (1ULL << 62)
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#define PME_FILE (1ULL << 61)
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#define PME_SOFT_DIRTY (1Ull << 55)
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struct mem_snap_ctx {
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unsigned long nr_iovs;
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struct iovec *iovs;
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unsigned long alloc;
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unsigned long rover;
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};
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#define MEM_SNAP_BATCH 64
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static int task_reset_dirty_track(int pid)
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{
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int fd, ret;
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char cmd[] = "4";
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if (!opts.mem_snapshot)
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return 0;
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pr_info("Reset %d's dirty tracking\n", pid);
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fd = open_proc_rw(pid, "clear_refs");
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if (fd < 0)
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return -1;
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ret = write(fd, cmd, sizeof(cmd));
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close(fd);
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if (ret < 0) {
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pr_perror("Can't reset %d's dirty memory tracker", pid);
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return -1;
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}
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pr_info(" ... done\n");
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return 0;
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}
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static struct mem_snap_ctx *mem_snap_init(struct parasite_ctl *ctl)
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{
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struct mem_snap_ctx *ctx;
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int p_fd, pm_fd;
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PagemapHead *h;
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if (!opts.mem_snapshot)
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return NULL;
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p_fd = get_service_fd(PARENT_FD_OFF);
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if (p_fd < 0) {
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pr_debug("Will do full memory dump\n");
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return NULL;
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}
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pm_fd = open_image_at(p_fd, CR_FD_PAGEMAP, O_RSTR, ctl->pid.virt);
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if (pm_fd < 0)
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return ERR_PTR(pm_fd);
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ctx = xmalloc(sizeof(*ctx));
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if (!ctx)
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goto err_cl;
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ctx->nr_iovs = 0;
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ctx->alloc = MEM_SNAP_BATCH;
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ctx->rover = 0;
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ctx->iovs = xmalloc(MEM_SNAP_BATCH * sizeof(struct iovec));
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if (!ctx->iovs)
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goto err_free;
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if (pb_read_one(pm_fd, &h, PB_PAGEMAP_HEAD) < 0)
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goto err_freei;
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pagemap_head__free_unpacked(h, NULL);
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while (1) {
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int ret;
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PagemapEntry *pe;
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ret = pb_read_one_eof(pm_fd, &pe, PB_PAGEMAP);
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if (ret == 0)
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break;
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if (ret < 0)
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goto err_freei;
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ctx->iovs[ctx->nr_iovs].iov_base = decode_pointer(pe->vaddr);
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ctx->iovs[ctx->nr_iovs].iov_len = pe->nr_pages * PAGE_SIZE;
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ctx->nr_iovs++;
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pagemap_entry__free_unpacked(pe, NULL);
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if (ctx->nr_iovs >= ctx->alloc) {
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ctx->iovs = xrealloc(ctx->iovs,
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(ctx->alloc + MEM_SNAP_BATCH) * sizeof(struct iovec));
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if (!ctx->iovs)
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goto err_freei;
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ctx->alloc += MEM_SNAP_BATCH;
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}
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}
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pr_info("Collected parent snap of %lu entries\n", ctx->nr_iovs);
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close(pm_fd);
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return ctx;
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err_freei:
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xfree(ctx->iovs);
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err_free:
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xfree(ctx);
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err_cl:
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close(pm_fd);
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return ERR_PTR(-1);
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}
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static void mem_snap_close(struct mem_snap_ctx *ctx)
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{
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if (ctx) {
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xfree(ctx->iovs);
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xfree(ctx);
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}
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}
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unsigned int vmas_pagemap_size(struct vm_area_list *vmas)
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{
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@ -41,9 +161,45 @@ static inline bool should_dump_page(VmaEntry *vmae, u64 pme)
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return false;
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}
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static int generate_iovs(struct vma_area *vma, int pagemap, struct page_pipe *pp, u64 *map)
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static int page_in_parent(unsigned long vaddr, u64 map, struct mem_snap_ctx *snap)
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{
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/*
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* Soft-dirty pages should be dumped here
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*/
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if (map & PME_SOFT_DIRTY)
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return 0;
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/*
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* Non soft-dirty should be present in parent map.
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* Otherwise pagemap is screwed up.
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*/
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while (1) {
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struct iovec *iov;
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iov = &snap->iovs[snap->rover];
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if ((unsigned long)iov->iov_base > vaddr)
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break;
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if ((unsigned long)iov->iov_base + iov->iov_len > vaddr)
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return 1;
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snap->rover++;
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if (snap->rover >= snap->nr_iovs)
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break;
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}
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pr_warn("Page %lx not in parent snap range (rover %lu).\n"
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"Dumping one, but the pagemap is screwed up.\n",
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vaddr, snap->rover);
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return 0;
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}
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static int generate_iovs(struct vma_area *vma, int pagemap, struct page_pipe *pp, u64 *map,
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struct mem_snap_ctx *snap)
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{
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unsigned long pfn, nr_to_scan;
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unsigned long pages[2] = {};
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u64 aux;
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aux = vma->vma.start / PAGE_SIZE * sizeof(*map);
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@ -60,13 +216,26 @@ static int generate_iovs(struct vma_area *vma, int pagemap, struct page_pipe *pp
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}
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for (pfn = 0; pfn < nr_to_scan; pfn++) {
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unsigned long vaddr;
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int ret;
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if (!should_dump_page(&vma->vma, map[pfn]))
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continue;
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if (page_pipe_add_page(pp, vma->vma.start + pfn * PAGE_SIZE))
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vaddr = vma->vma.start + pfn * PAGE_SIZE;
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if (snap && page_in_parent(vaddr, map[pfn], snap)) {
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ret = page_pipe_add_hole(pp, vaddr);
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pages[0]++;
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} else {
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ret = page_pipe_add_page(pp, vaddr);
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pages[1]++;
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}
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if (ret)
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return -1;
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}
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pr_info("Pagemap generated: %lu pages %lu holes\n", pages[1], pages[0]);
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return 0;
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}
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@ -109,6 +278,7 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
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struct vma_area *vma_area;
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int ret = -1;
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struct page_xfer xfer;
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struct mem_snap_ctx *snap;
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pr_info("\n");
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pr_info("Dumping pages (type: %d pid: %d)\n", CR_FD_PAGES, ctl->pid.real);
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@ -117,13 +287,17 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
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pr_debug(" Private vmas %lu/%lu pages\n",
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vma_area_list->longest, vma_area_list->priv_size);
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snap = mem_snap_init(ctl);
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if (IS_ERR(snap))
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goto out;
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args = parasite_args_s(ctl, vmas_pagemap_size(vma_area_list));
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map = xmalloc(vma_area_list->longest * sizeof(*map));
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if (!map)
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goto out;
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goto out_snap;
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ret = pagemap = open_proc(ctl->pid.real, "pagemap");
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ret = pagemap = open_proc(ctl->pid.real, "pagemap2");
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if (ret < 0)
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goto out_free;
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@ -136,7 +310,7 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
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if (!privately_dump_vma(vma_area))
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continue;
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ret = generate_iovs(vma_area, pagemap, pp, map);
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ret = generate_iovs(vma_area, pagemap, pp, map, snap);
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if (ret < 0)
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goto out_pp;
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}
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@ -166,12 +340,15 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
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ret = page_xfer_dump_pages(&xfer, pp, 0);
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xfer.close(&xfer);
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task_reset_dirty_track(ctl->pid.real);
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out_pp:
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destroy_page_pipe(pp);
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out_close:
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close(pagemap);
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out_free:
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xfree(map);
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out_snap:
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mem_snap_close(snap);
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out:
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pr_info("----------------------------------------\n");
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return ret;
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@ -286,6 +286,8 @@ static int write_pagehole_loc(struct page_xfer *xfer, struct iovec *iov)
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pe.vaddr = encode_pointer(iov->iov_base);
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pe.nr_pages = iov->iov_len / PAGE_SIZE;
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pe.has_in_parent = true;
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pe.in_parent = true;
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if (pb_write_one(xfer->fd, &pe, PB_PAGEMAP) < 0)
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return -1;
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