Support MADV_GUARD_INSTALL

[mihalicyn]

#2625

• https://lwn.net/Articles/1011366/
• torvalds/linux@662df3e
• bminor/glibc@a6fbe36

The following patch set extends the PAGEMAP_SCAN ioctl with PAGE_IS_GUARD flag to expose information about guard regions, allowing CRIU to detect and handle guard regions: https://lkml.org/lkml/2025/3/24/168

[minhbq-99]

Let me handle this issue.

[mihalicyn]

Hi @minhbq-99!

Let me handle this issue.

@avagin and I looking into this right now we'll get back to you if any help is needed.

LKML thread:
https://lore.kernel.org/criu/zihwmp67m2lpuxbfktmztvjdyap7suzd75dowlw4eamu6bhjf3@6euydiqowc7h/T/#u

[minhbq-99]

Okay, that's fine.

[minhbq-99]

LKML thread:
https://lore.kernel.org/criu/zihwmp67m2lpuxbfktmztvjdyap7suzd75dowlw4eamu6bhjf3@6euydiqowc7h/T/#u

Oh, at first, I think that there is some information about this region in /proc/pid/smaps like some other madvise region already. So it looks like if the user is using kernel with madvise(MADV_GUARD_INSTALL) but no information in /proc/pid/pagemap, it is quite hard to detect in CRIU.

[rst0git]

For reference, the following patch adds a guard region bit to the pagemap that we can use in CRIU:
https://lore.kernel.org/all/cover.1740139449.git.lorenzo.stoakes@oracle.com/T/#u

[mihalicyn]

https://lore.kernel.org/linux-fsdevel/20250320063903.2685882-1-avagin@google.com/

I'll be working on a CRIU part.

[rst0git]

Thanks @mihalicyn! Please feel free to open a draft pull request!