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kerndat: add pagemap_scan_guard_pages feature check logic

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Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
This commit is contained in:
Alexander Mikhalitsyn 2025-04-19 20:36:45 +02:00 committed by Radostin Stoyanov
parent 54c078e6c2
commit 66b46e5988
4 changed files with 24 additions and 0 deletions
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8
criu/cr-check.c
View File

@ -1599,6 +1599,12 @@ static int check_breakpoints(void)
return 0;
}
static int check_pagemap_scan_guard_pages(void)
{
kerndat_warn_about_madv_guards();
return kdat.has_pagemap_scan_guard_pages ? 0 : -1;
}
static int (*chk_feature)(void);
@ -1724,6 +1730,7 @@ int cr_check(void)
ret |= check_pagemap_scan();
ret |= check_overlayfs_maps();
ret |= check_timer_cr_ids();
ret |= check_pagemap_scan_guard_pages();
if (kdat.lsm == LSMTYPE__APPARMOR)
ret |= check_apparmor_stacking();
@ -1853,6 +1860,7 @@ static struct feature_list feature_list[] = {
{ "timer_cr_ids", check_timer_cr_ids },
{ "overlayfs_maps", check_overlayfs_maps },
{ "breakpoints", check_breakpoints },
{ "pagemap_scan_guard_pages", check_pagemap_scan_guard_pages },
{ NULL, NULL },
};

3
criu/include/kerndat.h
View File

@ -92,6 +92,7 @@ struct kerndat_s {
bool has_timer_cr_ids;
bool has_breakpoints;
bool has_madv_guard;
bool has_pagemap_scan_guard_pages;
};
extern struct kerndat_s kdat;
@ -114,4 +115,6 @@ extern int kerndat_fs_virtualized(unsigned int which, u32 kdev);
extern int kerndat_has_nspid(void);
extern void kerndat_warn_about_madv_guards(void);
#endif /* __CR_KERNDAT_H__ */

1
criu/include/pagemap_scan.h
View File

@ -14,6 +14,7 @@
#define PAGE_IS_PFNZERO (1 << 5)
#define PAGE_IS_HUGE (1 << 6)
#define PAGE_IS_SOFT_DIRTY (1 << 7)
#define PAGE_IS_GUARD (1 << 8)
/*
* struct page_region - Page region with flags

12
criu/kerndat.c
View File

@ -87,6 +87,10 @@ static int check_pagemap(void)
if (ioctl(fd, PAGEMAP_SCAN, &args) == 0) {
pr_debug("PAGEMAP_SCAN is supported\n");
kdat.has_pagemap_scan = true;
args.return_mask |= PAGE_IS_GUARD;
if (ioctl(fd, PAGEMAP_SCAN, &args) == 0)
kdat.has_pagemap_scan_guard_pages = true;
} else {
switch (errno) {
case EINVAL:
@ -1841,6 +1845,14 @@ mmap_cleanup:
return -1;
}
void kerndat_warn_about_madv_guards(void)
{
if (kdat.has_madv_guard && !kdat.has_pagemap_scan_guard_pages)
pr_warn("ioctl(PAGEMAP_SCAN) doesn't support PAGE_IS_GUARD flag. "
"CRIU dump will fail if dumped processes use madvise(MADV_GUARD_INSTALL). "
"Please, consider updating your kernel.\n");
}
/*
* Some features depend on resource that can be dynamically changed
* at the OS runtime. There are cases that we cannot determine the