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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: g3f67g6p736mz8ozmmfjc39w7jwoge77 X-Rspamd-Queue-Id: 12289C0009 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1761671772-808807 X-HE-Meta: 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 +0gnTPc2 TFZvlnyRd8KYmNWWP037QKMHH2Lfds2q918mEMcK+6tzuAi1u7P+H8OeJ6+KVI+34zQHNjKke1vule8DyBHeo8oPBMGaQ9GPVknwvlhU9ztlNbRybBvixRItoNd2mMkTcaSwmIgIAbC/kxKx/xtgIEQd9FkSzsA4TJ0eXLTGDQrJB4gYw2n0Y/NJFdS0xZFarqw7Ea02EatmiahsQ40Tks1bDh8FaenLboLrd+fMbxldrRcI5gmGO9bm33PkpIMUeKkhzl1m4m6WWHA/TB2E0MIqLndfRUPpd5Ai+BDoPvfL59eJrs/EjtUqhiMlliYyyGOml1X4zNEPaqiqMrDrl1CiOZZ2c5DZjah4o+H3I389lLxdIaszhfatt/kz3aif4jfWUL+U4T9ujh0EB/rWG9dijuhjI7NMcGpWHoE4gWiZjZwD6A99PGIUmX1Gxxp3jr9p9htXu9nzNZoYFnOk2QlXQBuwlGuEYmxV+ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025-10-28 13:02, Heiko Carstens wrote: > On Tue, Oct 28, 2025 at 04:48:57PM +0000, Joao Martins wrote: >> On 28/10/2025 16:14, Heiko Carstens wrote: >>> On Tue, Oct 28, 2025 at 04:05:45PM +0000, Joao Martins wrote: >>>>> +static inline void vmemmap_flush_tlb_all(void) >>>>> +{ >>>>> +#ifdef CONFIG_S390 >>>>> + __tlb_flush_kernel(); >>>>> +#else >>>>> + flush_tlb_all(); >>>>> +#endif >>>>> +} >>>>> + >>>> >>>> Wouldn't a better fix be to implement flush_tlb_all() in >>>> s390/include/asm/tlbflush.h since that aliases to __tlb_flush_kernel()? >>> >>> The question is rather what is flush_tlb_all() supposed to flush? Is >>> it supposed to flush only tlb entries corresponding to the kernel >>> address space, or should it flush just everything? >>> >> The latter i.e. everything >> >> At least as far as I understand >> >>> Within this context it looks like only tlb flushing for the kernel >>> address space is required(?) >> >> That's correct. We are changing the vmemmap which is in the kernel address >> space, so that's the intent. >> >> flush_tlb_all() however is the *closest* equivalent to this that's behind an >> arch generic API i.e. flushing kernel address space on all CPUs TLBs. IIUC, x86 >> when doing flush_tlb_kernel_range with enough pages it switches to flush_tlb_all >> (these days on modern AMDs it's even one instruction solely in the calling CPU). > > Considering that flush_tlb_all() should be mapped to __tlb_flush_global() > and not __tlb_flush_kernel() on s390. You're right. > However if there is only a need to flush tlb entries for the complete(?) > kernel address space, then I'd rather propose a new tlb_flush_kernel() > instead of a big hammer. If I'm not mistaken flush_tlb_kernel_range() > exists for just avoiding that. And if architectures can avoid a global > flush of _all_ tlb entries then that should be made possible. Should we take a v2 doing your suggestion above for now and work on the tlb_flush_kernel() idea as a follow up improvement? At least we go from crashing to flushing more than we should...