[CRIU] [PATCH] vmsplice user-buffer(grabbed by process_vm_readv) to page-pipe
Abhishek Dubey
dubeyabhishek777 at gmail.com
Thu Jul 4 21:47:59 MSK 2019
This patch implements usage of process_vm_readv syscall to collect memory
pages from target process during pre-dump. process_vm_readv collects pages
in user-buffer, which is later vmspliced to page-pipes.
Signed-off-by: Abhishek Dubey <dubeyabhishek777 at gmail.com>
---
criu/cr-dump.c | 3 +-
criu/include/page-xfer.h | 2 +-
criu/mem.c | 88
++++++++++++++++++------------------------------
criu/page-pipe.c | 4 +--
criu/page-xfer.c | 62 ++++++++++++++++++++++++++++++++--
criu/shmem.c | 19 +++--------
6 files changed, 102 insertions(+), 76 deletions(-)
diff --git a/criu/cr-dump.c b/criu/cr-dump.c
index 7f2e5ed..ee5f4f3 100644
--- a/criu/cr-dump.c
+++ b/criu/cr-dump.c
@@ -1501,6 +1501,7 @@ static int cr_pre_dump_finish(int status)
struct parasite_ctl *ctl = dmpi(item)->parasite_ctl;
struct page_pipe *mem_pp;
struct page_xfer xfer;
+ size_t off = 0;
if (!ctl)
continue;
@@ -1512,7 +1513,7 @@ static int cr_pre_dump_finish(int status)
goto err;
mem_pp = dmpi(item)->mem_pp;
- ret = page_xfer_dump_pages(&xfer, mem_pp);
+ ret = page_xfer_dump_pages(item->pid->real, &xfer, mem_pp, &off);
xfer.close(&xfer);
diff --git a/criu/include/page-xfer.h b/criu/include/page-xfer.h
index fa72273..74d42f2 100644
--- a/criu/include/page-xfer.h
+++ b/criu/include/page-xfer.h
@@ -47,7 +47,7 @@ struct page_xfer {
extern int open_page_xfer(struct page_xfer *xfer, int fd_type, unsigned
long id);
struct page_pipe;
-extern int page_xfer_dump_pages(struct page_xfer *, struct page_pipe *);
+extern int page_xfer_dump_pages(int pid, struct page_xfer *, struct
page_pipe *, size_t *poff);
extern int connect_to_page_server_to_send(void);
extern int connect_to_page_server_to_recv(int epfd);
extern int disconnect_from_page_server(void);
diff --git a/criu/mem.c b/criu/mem.c
index 6a1a87a..844d726 100644
--- a/criu/mem.c
+++ b/criu/mem.c
@@ -260,39 +260,7 @@ static struct parasite_dump_pages_args
*prep_dump_pages_args(struct parasite_ctl
return args;
}
-static int drain_pages(struct page_pipe *pp, struct parasite_ctl *ctl,
- struct parasite_dump_pages_args *args)
-{
- struct page_pipe_buf *ppb;
- int ret = 0;
-
- debug_show_page_pipe(pp);
-
- /* Step 2 -- grab pages into page-pipe */
- list_for_each_entry(ppb, &pp->bufs, l) {
- args->nr_segs = ppb->nr_segs;
- args->nr_pages = ppb->pages_in;
- pr_debug("PPB: %d pages %d segs %u pipe %d off\n",
- args->nr_pages, args->nr_segs, ppb->pipe_size, args->off);
-
- ret = compel_rpc_call(PARASITE_CMD_DUMPPAGES, ctl);
- if (ret < 0)
- return -1;
- ret = compel_util_send_fd(ctl, ppb->p[1]);
- if (ret)
- return -1;
-
- ret = compel_rpc_sync(PARASITE_CMD_DUMPPAGES, ctl);
- if (ret < 0)
- return -1;
-
- args->off += args->nr_segs;
- }
-
- return 0;
-}
-
-static int xfer_pages(struct page_pipe *pp, struct page_xfer *xfer)
+static int xfer_pages( int pid, struct page_pipe *pp, struct page_xfer
*xfer, size_t *poff)
{
int ret;
@@ -301,7 +269,7 @@ static int xfer_pages(struct page_pipe *pp, struct
page_xfer *xfer)
* pre-dump action (see pre_dump_one_task)
*/
timing_start(TIME_MEMWRITE);
- ret = page_xfer_dump_pages(xfer, pp);
+ ret = page_xfer_dump_pages(pid, xfer, pp, poff);
timing_stop(TIME_MEMWRITE);
return ret;
@@ -351,7 +319,7 @@ static int generate_vma_iovs(struct pstree_item *item,
struct vma_area *vma,
struct page_pipe *pp, struct page_xfer *xfer,
struct parasite_dump_pages_args *args,
struct parasite_ctl *ctl, pmc_t *pmc,
- bool has_parent, bool pre_dump)
+ bool has_parent, bool pre_dump, size_t *poff)
{
u64 off = 0;
u64 *map;
@@ -361,6 +329,12 @@ static int generate_vma_iovs(struct pstree_item *item,
struct vma_area *vma,
!vma_area_is(vma, VMA_ANON_SHARED))
return 0;
+ if (!(vma->e->prot & PROT_READ)){
+ if(pre_dump)
+ return 0;
+ has_parent = false;
+ }
+
if (vma_entry_is(vma->e, VMA_AREA_AIORING)) {
if (pre_dump)
return 0;
@@ -379,9 +353,7 @@ again:
if (ret == -EAGAIN) {
BUG_ON(!(pp->flags & PP_CHUNK_MODE));
- ret = drain_pages(pp, ctl, args);
- if (!ret)
- ret = xfer_pages(pp, xfer);
+ ret = xfer_pages(item->pid->real, pp, xfer, poff);
if (!ret) {
page_pipe_reinit(pp);
goto again;
@@ -406,6 +378,7 @@ static int __parasite_dump_pages_seized(struct
pstree_item *item,
unsigned long pmc_size;
int possible_pid_reuse = 0;
bool has_parent;
+ size_t poff = 0;
pr_info("\n");
pr_info("Dumping pages (type: %d pid: %d)\n", CR_FD_PAGES,
item->pid->real);
@@ -470,11 +443,12 @@ static int __parasite_dump_pages_seized(struct
pstree_item *item,
/*
* Step 1 -- generate the pagemap
*/
+ poff = 0;
args->off = 0;
has_parent = !!xfer.parent && !possible_pid_reuse;
list_for_each_entry(vma_area, &vma_area_list->h, list) {
ret = generate_vma_iovs(item, vma_area, pp, &xfer, args, ctl,
- &pmc, has_parent, mdc->pre_dump);
+ &pmc, has_parent, mdc->pre_dump, &poff);
if (ret < 0)
goto out_xfer;
}
@@ -482,9 +456,8 @@ static int __parasite_dump_pages_seized(struct
pstree_item *item,
if (mdc->lazy)
memcpy(pargs_iovs(args), pp->iovs,
sizeof(struct iovec) * pp->nr_iovs);
- ret = drain_pages(pp, ctl, args);
- if (!ret && !mdc->pre_dump)
- ret = xfer_pages(pp, &xfer);
+ if(!mdc->pre_dump)
+ ret = xfer_pages(item->pid->real, pp, &xfer, &poff);
if (ret)
goto out_xfer;
@@ -529,17 +502,18 @@ int parasite_dump_pages_seized(struct pstree_item
*item,
*
* Afterwards -- reprotect memory back.
*/
+ if(!mdc->pre_dump){
+ pargs->add_prot = PROT_READ;
+ ret = compel_rpc_call_sync(PARASITE_CMD_MPROTECT_VMAS, ctl);
+ if (ret) {
+ pr_err("Can't dump unprotect vmas with parasite\n");
+ return ret;
+ }
- pargs->add_prot = PROT_READ;
- ret = compel_rpc_call_sync(PARASITE_CMD_MPROTECT_VMAS, ctl);
- if (ret) {
- pr_err("Can't dump unprotect vmas with parasite\n");
- return ret;
- }
-
- if (fault_injected(FI_DUMP_PAGES)) {
- pr_err("fault: Dump VMA pages failure!\n");
- return -1;
+ if (fault_injected(FI_DUMP_PAGES)) {
+ pr_err("fault: Dump VMA pages failure!\n");
+ return -1;
+ }
}
ret = __parasite_dump_pages_seized(item, pargs, vma_area_list, mdc, ctl);
@@ -549,10 +523,12 @@ int parasite_dump_pages_seized(struct pstree_item
*item,
return ret;
}
- pargs->add_prot = 0;
- if (compel_rpc_call_sync(PARASITE_CMD_MPROTECT_VMAS, ctl)) {
- pr_err("Can't rollback unprotected vmas with parasite\n");
- ret = -1;
+ if(!mdc->pre_dump){
+ pargs->add_prot = 0;
+ if (compel_rpc_call_sync(PARASITE_CMD_MPROTECT_VMAS, ctl)) {
+ pr_err("Can't rollback unprotected vmas with parasite\n");
+ ret = -1;
+ }
}
return ret;
diff --git a/criu/page-pipe.c b/criu/page-pipe.c
index c32b893..c70ba70 100644
--- a/criu/page-pipe.c
+++ b/criu/page-pipe.c
@@ -33,7 +33,7 @@ static int __ppb_resize_pipe(struct page_pipe_buf *ppb,
unsigned long new_size)
{
int ret;
- ret = fcntl(ppb->p[0], F_SETPIPE_SZ, new_size * PAGE_SIZE);
+ ret = fcntl(ppb->p[0], F_SETPIPE_SZ, (new_size * PAGE_SIZE) + 1);
if (ret < 0)
return -1;
@@ -41,7 +41,7 @@ static int __ppb_resize_pipe(struct page_pipe_buf *ppb,
unsigned long new_size)
BUG_ON(ret < ppb->pipe_size);
pr_debug("Grow pipe %x -> %x\n", ppb->pipe_size, ret);
- ppb->pipe_size = ret;
+ ppb->pipe_size = ret - 1;
return 0;
}
diff --git a/criu/page-xfer.c b/criu/page-xfer.c
index 9cdffd8..9262221 100644
--- a/criu/page-xfer.c
+++ b/criu/page-xfer.c
@@ -496,19 +496,75 @@ static inline u32 ppb_xfer_flags(struct page_xfer
*xfer, struct page_pipe_buf *p
return PE_PRESENT;
}
-int page_xfer_dump_pages(struct page_xfer *xfer, struct page_pipe *pp)
+static char userbuf[4 << 20];
+
+int page_xfer_dump_pages(int pid, struct page_xfer *xfer, struct page_pipe
*pp, size_t *poff)
{
struct page_pipe_buf *ppb;
unsigned int cur_hole = 0;
- int ret;
+ unsigned int ret, ret2;
+ size_t off;
+ struct iovec *remoteiovs = pp->iovs;
pr_debug("Transferring pages:\n");
+ off = *poff;
+
list_for_each_entry(ppb, &pp->bufs, l) {
unsigned int i;
pr_debug("\tbuf %d/%d\n", ppb->pages_in, ppb->nr_segs);
+ size_t bufsize = sizeof(userbuf);
+ struct iovec bufvec = {.iov_len = bufsize};
+ bufvec.iov_base = userbuf;
+
+ ret = syscall(__NR_process_vm_readv, pid, &bufvec, 1, \
+ &remoteiovs[off], ppb->nr_segs, 0);
+ if (ret < 0) {
+ switch (errno) {
+ case EINVAL:
+ pr_debug("process_vm_readv: Invalid arguments\n");
+ break;
+ case EFAULT:
+ pr_debug("process_vm_readv: Unable to access remote iov\n");
+ break;
+ case ENOMEM:
+ pr_debug("process_vm_readv: Unable to allocate memory\n");
+ break;
+ case EPERM:
+ pr_debug("process_vm_readv: Insufficient privileges\n");
+ break;
+ case ESRCH:
+ pr_debug("process_vm_readv: Target process doesn't exist\n");
+ break;
+ default:
+ pr_debug("process_vm_readv: Uncategorised error\n");
+ }
+ return 0;
+ }
+
+ /* Handling partial reads due to modified mappings*/
+
+ if(ret != ppb->pages_in * PAGE_SIZE){
+ pr_debug("Can't read remote iovs (%d(%lu)/%d)\n", ret,\
+ (unsigned long int)PAGE_SIZE * ppb->pages_in, ppb->pages_in);
+ continue;
+ }
+
+ bufvec.iov_len = ret;
+ ret2 = vmsplice(ppb->p[1], &bufvec, 1, SPLICE_F_NONBLOCK);
+
+ if(ret2 == -1){
+ pr_debug("vmsplice: Failed to splice user buffer to pipe\n");
+ continue;
+ }
+
+ if(ret != ret2){
+ pr_debug("Partial splice from user buffer to pipe (%d)\n", ret2);
+ continue;
+ }
+
for (i = 0; i < ppb->nr_segs; i++) {
struct iovec iov = ppb->iov[i];
u32 flags;
@@ -530,8 +586,10 @@ int page_xfer_dump_pages(struct page_xfer *xfer,
struct page_pipe *pp)
ppb->p[0], iov.iov_len))
return -1;
}
+ off += ppb->nr_segs;
}
+ *poff = off;
return dump_holes(xfer, pp, &cur_hole, NULL);
}
diff --git a/criu/shmem.c b/criu/shmem.c
index 03b088f..a797bde 100644
--- a/criu/shmem.c
+++ b/criu/shmem.c
@@ -629,19 +629,9 @@ int add_shmem_area(pid_t pid, VmaEntry *vma, u64 *map)
return 0;
}
-static int dump_pages(struct page_pipe *pp, struct page_xfer *xfer)
+static int dump_pages(struct page_pipe *pp, struct page_xfer *xfer, size_t
*off)
{
- struct page_pipe_buf *ppb;
-
- list_for_each_entry(ppb, &pp->bufs, l)
- if (vmsplice(ppb->p[1], ppb->iov, ppb->nr_segs,
- SPLICE_F_GIFT | SPLICE_F_NONBLOCK) !=
- ppb->pages_in * PAGE_SIZE) {
- pr_perror("Can't get shmem into page-pipe");
- return -1;
- }
-
- return page_xfer_dump_pages(xfer, pp);
+ return page_xfer_dump_pages(getpid(), xfer, pp, off);
}
static int next_data_segment(int fd, unsigned long pfn,
@@ -678,6 +668,7 @@ static int do_dump_one_shmem(int fd, void *addr, struct
shmem_info *si)
int err, ret = -1;
unsigned long pfn, nrpages, next_data_pnf = 0, next_hole_pfn = 0;
unsigned long pages[2] = {};
+ size_t off = 0;
nrpages = (si->size + PAGE_SIZE - 1) / PAGE_SIZE;
@@ -726,7 +717,7 @@ again:
}
if (ret == -EAGAIN) {
- ret = dump_pages(pp, &xfer);
+ ret = dump_pages(pp, &xfer, &off);
if (ret)
goto err_xfer;
page_pipe_reinit(pp);
@@ -742,7 +733,7 @@ again:
cnt_add(CNT_SHPAGES_SKIPPED_PARENT, pages[0]);
cnt_add(CNT_SHPAGES_WRITTEN, pages[1]);
- ret = dump_pages(pp, &xfer);
+ ret = dump_pages(pp, &xfer, &off);
err_xfer:
xfer.close(&xfer);
--
2.7.4
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