On 8/1/25 15:40, Alexander Krabler wrote: > On 8/1/25 14:57, Vlastimil Babka wrote: >> Hm that means something isn't working as intended. Do the pages have also >> the unevictable flag? > > I have checked /proc/<pid>/smaps. > Neither the manpage (https://www.man7.org/linux/man-pages/man5/proc_pid_smaps.5.html) > nor kernel source code (fs/proc/task_mmu.c show_smap_vma_flags) tells me about unevictable flag. Ah ok, you checked /proc/pid/smaps. Since you said "pages" I thought you meant individual pages which would be from /proc/kpageflags But IIRC getting a page in a state where it has an mlock flag but (not yet) the unevictable flag should be rare so I would be surprised if that was the problem here. Hm or maybe it's actually that the error can happen only in the other direction - page is unevictable (on unevictable list) while not mlocked, at least the counters such as UNEVICTABLE_PGRESCUED suggest that. Hugh knows this code the best. Do you think we should e.g. test the mlocked flag instead/in addition to unevictable flag in compaction to avoid violating vm.compact_unevictable_allowed = 0?
