On Fri, 2018-06-15 at 01:38:37 UTC, Nicholas Piggin wrote:
> The patch 99baac21e4 ("mm: fix MADV_[FREE|DONTNEED] TLB flush miss
> problem") added a force flush mode to the mmu_gather flush, which
> unconditionally flushes the entire address range being invalidated
> (even if actual ptes only covered a smaller range), to solve a problem
> with concurrent threads invalidating the same PTEs causing them to
> miss TLBs that need flushing.
>
> This does not work with powerpc that invalidates mmu_gather batches
> according to page size. Have powerpc flush all possible page sizes in
> the range if it encounters this concurrency condition.
>
> Patch 4647706ebe ("mm: always flush VMA ranges affected by
> zap_page_range") does add a TLB flush for all page sizes on powerpc for
> the zap_page_range case, but that is to be removed and replaced with
> the mmu_gather flush to avoid redundant flushing. It is also thought to
> not cover other obscure race conditions:
>
> https://lkml.kernel.org/r/bd3a0ebe-ecf4-41d4-87fa-c755ea9ab...@gmail.com
>
> Hash does not have a problem because it invalidates TLBs inside the
> page table locks.
>
> Reported-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/02390f66bd2362df114a0a0770d80e
cheers
