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pagemap-cache: Use greedy mode if pagemap inaccessible

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If criu is running in unprivileged mode and we can't
access dumpee's pagemap file -- simply switch to
greedy mode where all pages are gonna be dumped
regardless of their presence in memory.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Looks-good-to-me: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Cyrill Gorcunov
2015-12-15 22:25:44 +03:00
committed by Pavel Emelyanov
parent d1db4faf9b
commit a4edef8e1c
1 changed files with 29 additions and 11 deletions
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32
pagemap-cache.c
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@@ -39,20 +39,29 @@ int pmc_init(pmc_t *pmc, pid_t pid, const struct list_head *vma_head, size_t siz
BUG_ON(!vma_head);
pmc->pid = pid;
pmc->fd = open_proc(pid, "pagemap");
pmc->map_len = PAGEMAP_LEN(map_size);
pmc->map = xmalloc(pmc->map_len);
pmc->vma_head = vma_head;
if (!pmc->map || pmc->fd < 0) {
pr_err("Failed to init pagemap for %d\n", pid);
pmc_fini(pmc);
return -1;
pmc->map = xmalloc(pmc->map_len);
if (!pmc->map)
goto err;
pmc->fd = __open_proc(pid, EPERM, O_RDONLY, "pagemap");
if (pmc->fd < 0) {
if (errno != EPERM)
goto err;
pr_warn("No pagemap for %d available, "
"switching to greedy mode\n", pid);
}
pr_debug("created for pid %d (takes %zu bytes)\n", pid, pmc->map_len);
return 0;
err:
pr_err("Failed to init pagemap for %d\n", pid);
pmc_fini(pmc);
return -1;
}
static inline u64 *__pmc_get_map(pmc_t *pmc, unsigned long addr)
@@ -120,11 +129,20 @@ static int pmc_fill_cache(pmc_t *pmc, const struct vma_area *vma)
size_map = PAGEMAP_LEN(pmc->end - pmc->start);
BUG_ON(pmc->map_len < size_map);
if (unlikely(pmc->fd < 0)) {
/*
* We don't have access to the dumpee pagemap so fill
* everything as present. It's better than refuse
* to dump because it simply disables optimisation.
*/
memset(pmc->map, 1, size_map);
} else {
if (pread(pmc->fd, pmc->map, size_map, PAGEMAP_PFN_OFF(pmc->start)) != size_map) {
pmc_zap(pmc);
pr_perror("Can't read %d's pagemap file", pmc->pid);
return -1;
}
}
return 0;
}