On Fri, 24 Apr 2026 13:37:04 +0000 Pasha Tatashin <[email protected]> wrote:
> On 04-24 06:30, Andrew Morton wrote: > > On Fri, 24 Apr 2026 14:25:26 +0800 Lance Yang <[email protected]> wrote: > > > > > When page table operations require synchronization with software/lockless > > > walkers, they call tlb_remove_table_sync_{one,rcu}() after flushing the > > > TLB (tlb->freed_tables or tlb->unshared_tables). > > > > > > On architectures where the TLB flush already sends IPIs to all target > > > CPUs, > > > the subsequent sync IPI broadcast is redundant. This is not only costly on > > > large systems where it disrupts all CPUs even for single-process page > > > table > > > operations, but has also been reported to hurt RT workloads[1]. > > > > > > This series introduces tlb_table_flush_implies_ipi_broadcast() to check if > > > the prior TLB flush already provided the necessary synchronization. When > > > true, the sync calls can early-return. > > > > > > A few cases rely on this synchronization: > > > > > > 1) hugetlb PMD unshare[2]: The problem is not the freeing but the reuse > > > of the PMD table for other purposes in the last remaining user after > > > unsharing. > > > > > > 2) khugepaged collapse[3]: Ensure no concurrent GUP-fast before collapsing > > > and (possibly) freeing the page table / re-depositing it. > > > > Sashiko questions: > > > > https://sashiko.dev/#/patchset/[email protected] > > > > (I never know if my Sashiko emails are welcome/useful. Maybe Sashiko > > said the same stuff about v9 and it's all wrong. But better safe than > > sorry!) > > These emails are helpful; but, I do not believe you should have to > manually follow up with a link to every new patch series. > > Perhaps Sashiko could automatically send a summary email in response to > the cover letter, or provide a link once the reviews are complete. For > the kexec ML, we opted-in with Roman to receive automated emails from > sashiko. Yep. I'd be OK with an automatic reply-to-all. Maybe some won't like that. An alternative I've discussed with Roman is an automated reply-to-author with a cc to a dedicated list (we could use mm-commits for now). Preferences? (I'd suggest automated-reply-to-all, see who complains, then figure out why they can't figure out mail filtering ;))
