On Thu, Mar 12, 2020 at 06:57:39PM +0530, Santosh Sivaraj wrote:
> From: Peter Zijlstra <pet...@infradead.org>
>
> commit 0ed1325967ab5f7a4549a2641c6ebe115f76e228 upstream.
>
> Architectures for which we have hardware walkers of Linux page table
> should flush TLB on mmu gather batch allocation failures and batch flush.
> Some architectures like POWER supports multiple translation modes (hash
> and radix) and in the case of POWER only radix translation mode needs the
> above TLBI. This is because for hash translation mode kernel wants to
> avoid this extra flush since there are no hardware walkers of linux page
> table. With radix translation, the hardware also walks linux page table
> and with that, kernel needs to make sure to TLB invalidate page walk cache
> before page table pages are freed.
>
> More details in commit d86564a2f085 ("mm/tlb, x86/mm: Support invalidating
> TLB caches for RCU_TABLE_FREE")
>
> The changes to sparc are to make sure we keep the old behavior since we
> are now removing HAVE_RCU_TABLE_NO_INVALIDATE. The default value for
> tlb_needs_table_invalidate is to always force an invalidate and sparc can
> avoid the table invalidate. Hence we define tlb_needs_table_invalidate to
> false for sparc architecture.
>
> Link:
> http://lkml.kernel.org/r/20200116064531.483522-3-aneesh.ku...@linux.ibm.com
> Fixes: a46cc7a90fd8 ("powerpc/mm/radix: Improve TLB/PWC flushes")
> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org
> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
> Cc: <sta...@vger.kernel.org> # 4.19
> Signed-off-by: Santosh Sivaraj <sant...@fossix.org>
> [santosh: backported to 4.19 stable]
> ---
> arch/Kconfig | 3 ---
> arch/powerpc/Kconfig | 1 -
> arch/powerpc/include/asm/tlb.h | 11 +++++++++++
> arch/sparc/Kconfig | 1 -
> arch/sparc/include/asm/tlb_64.h | 9 +++++++++
> include/asm-generic/tlb.h | 15 +++++++++++++++
> mm/memory.c | 16 ++++++++--------
> 7 files changed, 43 insertions(+), 13 deletions(-)
As the testing pointed out, this breaks the build on lots of arches:
https://lore.kernel.org/r/caeuse78+f1q9lfjpf8sqzqa6+ak4wcpiincuvxecv+kpdry...@mail.gmail.com
https://lore.kernel.org/r/cff87cd2-8cd5-241e-3a05-a817b1a56...@roeck-us.net
so I'm going to drop this whole series and do a -rc2.
If you still want/need this series in 4.19, please make sure it really
works for everyone :)
thanks,
greg k-h
