On Thu, Oct 24, 2024 at 06:04:41PM +0200, Vlastimil Babka wrote: > Petr suggested the same, but changing __thp_get_unmapped_area() affects FS > THP's and the proposed check seemed wrong to me: > > https://lore.kernel.org/all/9d7c73f6-1e1a-458b-93c6-3b44959022e0@xxxxxxx/ > > While it could be fixed, I'm still not sure if we want to restrict FS THPs > the same as anonymous THPs. AFAIU even small mappings of a range from a file > should be aligned properly to make it possible for a large range from the > same file (that includes the smaller range) mapped elsewhere to be THP > backed? I mean we can investigate it further, but for the regression fix to > backported to stable kernels it seemed more safe to address only the case > that was changed by commit efa7df3e3bb5 specifically, i.e. anonymous mappings. > Ack, yeah totally agreed - sorry I missed the fs usage before, see my 2nd reply. I had wrongly assumed this was only used in 1 place, where it would be sensible to move the check, however with fs using it of course it's not. Gave an R-b tag on other reply so this patch LGTM! :) Cheers for finding this utterly critical fix!
