Potential future breakage on linux

hoytech / vmtouch

Portable file system cache diagnostics and control

https://hoytech.com/vmtouch/

BSD 3-Clause "New" or "Revised" License

1.79k stars 210 forks source link

Potential future breakage on linux #74

Open hoytech opened 5 years ago

hoytech commented 5 years ago

It looks like mincore() may be crippled in new linux kernels to protect against side-channel attacks: see this linux kernel commit

Unfortunately, on kernel versions 5.2+, you'll need to run vmtouch as root to get accurate page-residency information on files you don't have write access to.

freedge commented 4 years ago

indeed, we experienced issue with SLES12 and kernel 4.12.14-95.24 - vmtouch would just report every single file as fully present in the page cache.

It's a bit messy, Linus committed, then reverted, a patch for mincore. Not sure how newer kernel versions will behave.