Re: [PATCH mk-II 08/17] asm-generic/tlb: Provide MMU_GATHER_TABLE_FREE

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On 1/27/20 1:41 PM, Peter Zijlstra wrote:
On Sun, Jan 26, 2020 at 07:52:05AM -0800, Guenter Roeck wrote:
On Thu, Dec 12, 2019 at 10:32:05AM +0100, Peter Zijlstra wrote:
As described in the comment, the correct order for freeing pages is:

  1) unhook page
  2) TLB invalidate page
  3) free page

This order equally applies to page directories.

Currently there are two correct options:

  - use tlb_remove_page(), when all page directores are full pages and
    there are no futher contraints placed by things like software
    walkers (HAVE_FAST_GUP).

  - use MMU_GATHER_RCU_TABLE_FREE and tlb_remove_table() when the
    architecture does not do IPI based TLB invalidate and has
    HAVE_FAST_GUP (or software TLB fill).

This however leaves architectures that don't have page based
directories but don't need RCU in a bind. For those, provide
MMU_GATHER_TABLE_FREE, which provides the independent batching for
directories without the additional RCU freeing.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---

Various sparc64 builds (allnoconfig, tinyconfig, as well as builds
with SMP disabled):

mm/mmu_gather.c: In function '__tlb_remove_table_free':
mm/mmu_gather.c:101:3: error: implicit declaration of function '__tlb_remove_table'; did you mean 'tlb_remove_table'?

Thanks; I'll respin these patches against Aneesh' pile and make sure to
look into this when I do so.



I did send a change to fix that. it is to drop !SMP change in the patch

https://lore.kernel.org/linux-mm/87v9p9mhnr.fsf@xxxxxxxxxxxxx


-aneesh





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