On Mon 25-06-18 14:56:26, Kani Toshimitsu wrote: > On Sun, 2018-06-24 at 15:19 +0200, Thomas Gleixner wrote: > > On Wed, 16 May 2018, Toshi Kani wrote: > > > > > This series fixes two issues in the x86 ioremap free page handlings > > > for pud/pmd mappings. > > > > > > Patch 01 fixes BUG_ON on x86-PAE reported by Joerg. It disables > > > the free page handling on x86-PAE. > > > > > > Patch 02-03 fixes a possible issue with speculation which can cause > > > stale page-directory cache. > > > - Patch 02 is from Chintan's v9 01/04 patch [1], which adds a new arg > > > 'addr', with my merge change to patch 01. > > > - Patch 03 adds a TLB purge (INVLPG) to purge page-structure caches > > > that may be cached by speculation. See the patch descriptions for > > > more detal. > > > > Toshi, Joerg, Michal! > > Hi Thomas, > > Thanks for checking. I was about to ping as well. > > > I'm failing to find a conclusion of this discussion. Can we finally make > > some progress with that? > > I have not heard from Joerg since I last replied to his comments to > Patch 3/3 -- I did my best to explain that there was no issue in the > single page allocation in pud_free_pmd_page(). From my perspective, the > v3 series is good to go. Well, I admit that this not my area but I agree with Joerg that allocating memory inside afunction that is supposed to free page table is far from ideal. More so that the allocation is hardcoded GFP_KERNEL. We already have this antipattern in functions to allocate page tables and it has turned to be maintenance PITA longterm. So if there is a way around that then I would strongly suggest finding a different solution. Whether that is sufficient to ditch the whole series is not my call though. -- Michal Hocko SUSE Labs
