On Monday 29 October 2012 08:53 PM, Rik van Riel wrote: > On 10/26/2012 03:18 PM, Linus Torvalds wrote: >> On Fri, Oct 26, 2012 at 12:16 PM, Rik van Riel <riel@xxxxxxxxxx> wrote: >>> >>> I can change the text of the changelog, however it looks >>> like do_wp_page does actually use ptep_set_access_flags >>> to set the write bit in the pte... >>> >>> I guess both need to be reflected in the changelog text >>> somehow? >> >> Yeah, and by now, after all this discussion, I suspect it should be >> committed with a comment too. Commit messages are good and all, but >> unless chasing a particular bug they introduced, we shouldn't expect >> people to read them for background information. > > Now that we have the TLB things taken care of, and > comments to patches 10/31 and 26/31 have been addressed, > is there anything else that needs to be done before > these NUMA patches can be merged? > > Anyone, this is a good time to speak up. We have some > time to address whatever concern you may have. > Hi, I know I'm very late in speaking up - but still I'll hazard a try. This is not exactly the same topic but closely related. There is a a different call to flush_tlb_fix_spurious( ), towards the end of handle_pte_fault( ) which commit 61c77326d "x86, mm: Avoid unnecessary TLB flush" made no-op for X86. However is this really needed for any arch at all - even if we don't know all the arch specific quirks. Given the code flow below handle_pte_fault( ) .... .... if ptep_set_access_flags()-> if PTE chg remote TLB shot (pgtable-generic.c ver) update_mmu_cache -> if PTE chg local TLB possibly shot too else flush_tlb_fix_spurious_fault -> PTE didn't change - still remote TLB shotdown So for PTE unchanged case, we default to doing remote TLB IPIs (barring X86) - unless arch makes this macro NULL. Thing is, in case of SMP races - due to PTE being different - any fixups to local/remote will be handled within ptep_set_access_flags( ) - arch-specific or generic versions. What I fail to understand is need to do anything - specially a remote shootdown, for PTE not changed case. I could shut up and just make it NO-OP for ARC, but .... Please note that for the record, the addition of this special case was done via following change. It might help answer what I feel to comprehend. 2005-10-29 1a44e14 [PATCH] .text page fault SMP scalability optimization I might be totally off track so please feel free to bash me - but atleast I would end up knowing more ! Thx, -Vineet -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>