[CRIU] [PATCH 6/9] dump: Snapshot memory
Pavel Emelyanov
xemul at parallels.com
Thu Apr 11 09:50:57 EDT 2013
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 at parallels.com>
---
mem.c | 187 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
page-xfer.c | 2 +
2 files changed, 184 insertions(+), 5 deletions(-)
diff --git a/mem.c b/mem.c
index f72d2db..7ab0f60 100644
--- a/mem.c
+++ b/mem.c
@@ -1,6 +1,7 @@
#include <unistd.h>
#include <stdio.h>
#include <sys/mman.h>
+#include <errno.h>
#include "crtools.h"
#include "mem.h"
@@ -10,9 +11,128 @@
#include "page-xfer.h"
#include "log.h"
+#include "protobuf.h"
+#include "protobuf/pagemap.pb-c.h"
+
#define PME_PRESENT (1ULL << 63)
#define PME_SWAP (1ULL << 62)
#define PME_FILE (1ULL << 61)
+#define PME_SOFT_DIRTY (1Ull << 55)
+
+struct mem_snap_ctx {
+ unsigned long nr_iovs;
+ struct iovec *iovs;
+ unsigned long alloc;
+ unsigned long rover;
+};
+
+#define MEM_SNAP_BATCH 64
+
+static int task_reset_dirty_track(int pid)
+{
+ int fd, ret;
+ char cmd[] = "4";
+
+ if (!opts.mem_snapshot)
+ return 0;
+
+ pr_info("Reset %d's dirty tracking\n", pid);
+ fd = open_proc_rw(pid, "clear_refs");
+ if (fd < 0)
+ return -1;
+
+ ret = write(fd, cmd, sizeof(cmd));
+ close(fd);
+
+ if (ret < 0) {
+ pr_perror("Can't reset %d's dirty memory tracker", pid);
+ return -1;
+ }
+
+ pr_info(" ... done\n");
+ return 0;
+}
+
+static struct mem_snap_ctx *mem_snap_init(struct parasite_ctl *ctl)
+{
+ struct mem_snap_ctx *ctx;
+ int p_fd, pm_fd;
+ PagemapHead *h;
+
+ if (!opts.mem_snapshot)
+ return NULL;
+
+ p_fd = get_service_fd(PARENT_FD_OFF);
+ if (p_fd < 0) {
+ pr_debug("Will do full memory dump\n");
+ return NULL;
+ }
+
+ pm_fd = open_image_at(p_fd, CR_FD_PAGEMAP, O_RSTR, ctl->pid.virt);
+ if (pm_fd < 0)
+ return ERR_PTR(pm_fd);
+
+ ctx = xmalloc(sizeof(*ctx));
+ if (!ctx)
+ goto err_cl;
+
+ ctx->nr_iovs = 0;
+ ctx->alloc = MEM_SNAP_BATCH;
+ ctx->rover = 0;
+ ctx->iovs = xmalloc(MEM_SNAP_BATCH * sizeof(struct iovec));
+ if (!ctx->iovs)
+ goto err_free;
+
+ if (pb_read_one(pm_fd, &h, PB_PAGEMAP_HEAD) < 0)
+ goto err_freei;
+
+ pagemap_head__free_unpacked(h, NULL);
+
+ while (1) {
+ int ret;
+ PagemapEntry *pe;
+
+ ret = pb_read_one_eof(pm_fd, &pe, PB_PAGEMAP);
+ if (ret == 0)
+ break;
+ if (ret < 0)
+ goto err_freei;
+
+ ctx->iovs[ctx->nr_iovs].iov_base = decode_pointer(pe->vaddr);
+ ctx->iovs[ctx->nr_iovs].iov_len = pe->nr_pages * PAGE_SIZE;
+ ctx->nr_iovs++;
+ pagemap_entry__free_unpacked(pe, NULL);
+
+ if (ctx->nr_iovs >= ctx->alloc) {
+ ctx->iovs = xrealloc(ctx->iovs,
+ (ctx->alloc + MEM_SNAP_BATCH) * sizeof(struct iovec));
+ if (!ctx->iovs)
+ goto err_freei;
+
+ ctx->alloc += MEM_SNAP_BATCH;
+ }
+ }
+
+ pr_info("Collected parent snap of %lu entries\n", ctx->nr_iovs);
+ close(pm_fd);
+ return ctx;
+
+err_freei:
+ xfree(ctx->iovs);
+err_free:
+ xfree(ctx);
+err_cl:
+ close(pm_fd);
+ return ERR_PTR(-1);
+}
+
+static void mem_snap_close(struct mem_snap_ctx *ctx)
+{
+ if (ctx) {
+ xfree(ctx->iovs);
+ xfree(ctx);
+ }
+}
unsigned int vmas_pagemap_size(struct vm_area_list *vmas)
{
@@ -41,9 +161,45 @@ static inline bool should_dump_page(VmaEntry *vmae, u64 pme)
return false;
}
-static int generate_iovs(struct vma_area *vma, int pagemap, struct page_pipe *pp, u64 *map)
+static int page_in_parent(unsigned long vaddr, u64 map, struct mem_snap_ctx *snap)
+{
+ /*
+ * Soft-dirty pages should be dumped here
+ */
+ if (map & PME_SOFT_DIRTY)
+ return 0;
+
+ /*
+ * Non soft-dirty should be present in parent map.
+ * Otherwise pagemap is screwed up.
+ */
+
+ while (1) {
+ struct iovec *iov;
+
+ iov = &snap->iovs[snap->rover];
+ if ((unsigned long)iov->iov_base > vaddr)
+ break;
+
+ if ((unsigned long)iov->iov_base + iov->iov_len > vaddr)
+ return 1;
+
+ snap->rover++;
+ if (snap->rover >= snap->nr_iovs)
+ break;
+ }
+
+ pr_warn("Page %lx not in parent snap range (rover %lu).\n"
+ "Dumping one, but the pagemap is screwed up.\n",
+ vaddr, snap->rover);
+ return 0;
+}
+
+static int generate_iovs(struct vma_area *vma, int pagemap, struct page_pipe *pp, u64 *map,
+ struct mem_snap_ctx *snap)
{
unsigned long pfn, nr_to_scan;
+ unsigned long pages[2] = {};
u64 aux;
aux = vma->vma.start / PAGE_SIZE * sizeof(*map);
@@ -60,13 +216,26 @@ static int generate_iovs(struct vma_area *vma, int pagemap, struct page_pipe *pp
}
for (pfn = 0; pfn < nr_to_scan; pfn++) {
+ unsigned long vaddr;
+ int ret;
+
if (!should_dump_page(&vma->vma, map[pfn]))
continue;
- if (page_pipe_add_page(pp, vma->vma.start + pfn * PAGE_SIZE))
+ vaddr = vma->vma.start + pfn * PAGE_SIZE;
+ if (snap && page_in_parent(vaddr, map[pfn], snap)) {
+ ret = page_pipe_add_hole(pp, vaddr);
+ pages[0]++;
+ } else {
+ ret = page_pipe_add_page(pp, vaddr);
+ pages[1]++;
+ }
+
+ if (ret)
return -1;
}
+ pr_info("Pagemap generated: %lu pages %lu holes\n", pages[1], pages[0]);
return 0;
}
@@ -109,6 +278,7 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
struct vma_area *vma_area;
int ret = -1;
struct page_xfer xfer;
+ struct mem_snap_ctx *snap;
pr_info("\n");
pr_info("Dumping pages (type: %d pid: %d)\n", CR_FD_PAGES, ctl->pid.real);
@@ -117,13 +287,17 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
pr_debug(" Private vmas %lu/%lu pages\n",
vma_area_list->longest, vma_area_list->priv_size);
+ snap = mem_snap_init(ctl);
+ if (IS_ERR(snap))
+ goto out;
+
args = parasite_args_s(ctl, vmas_pagemap_size(vma_area_list));
map = xmalloc(vma_area_list->longest * sizeof(*map));
if (!map)
- goto out;
+ goto out_snap;
- ret = pagemap = open_proc(ctl->pid.real, "pagemap");
+ ret = pagemap = open_proc(ctl->pid.real, "pagemap2");
if (ret < 0)
goto out_free;
@@ -136,7 +310,7 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
if (!privately_dump_vma(vma_area))
continue;
- ret = generate_iovs(vma_area, pagemap, pp, map);
+ ret = generate_iovs(vma_area, pagemap, pp, map, snap);
if (ret < 0)
goto out_pp;
}
@@ -166,12 +340,15 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
ret = page_xfer_dump_pages(&xfer, pp, 0);
xfer.close(&xfer);
+ task_reset_dirty_track(ctl->pid.real);
out_pp:
destroy_page_pipe(pp);
out_close:
close(pagemap);
out_free:
xfree(map);
+out_snap:
+ mem_snap_close(snap);
out:
pr_info("----------------------------------------\n");
return ret;
diff --git a/page-xfer.c b/page-xfer.c
index 0f3c26a..aeab1be 100644
--- a/page-xfer.c
+++ b/page-xfer.c
@@ -286,6 +286,8 @@ static int write_pagehole_loc(struct page_xfer *xfer, struct iovec *iov)
pe.vaddr = encode_pointer(iov->iov_base);
pe.nr_pages = iov->iov_len / PAGE_SIZE;
+ pe.has_in_parent = true;
+ pe.in_parent = true;
if (pb_write_one(xfer->fd, &pe, PB_PAGEMAP) < 0)
return -1;
--
1.7.11.7
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