On Dienstag, 14. Februar 2023 10:55:43 CET Alexandre Ghiti wrote: > Hi Matthew, > > On 2/7/23 21:27, Matthew Wilcox wrote: > > On Thu, Feb 02, 2023 at 09:14:23PM +0000, Matthew Wilcox wrote: > >> For those of you not subscribed, linux-mm is currently discussing > >> how best to handle page faults on large folios. I simply made it work > >> when adding large folio support. Now Yin Fengwei is working on > >> making it fast. > > > > OK, here's an actual implementation: > > > > https://lore.kernel.org/linux-mm/20230207194937.122543-3-willy@infradead.o > > rg/ > > > > It survives a run of xfstests. If your architecture doesn't store its > > PFNs at PAGE_SHIFT, you're going to want to implement your own set_ptes(), > > or you'll see entirely the wrong pages mapped into userspace. You may > > also wish to implement set_ptes() if it can be done more efficiently > > than __pte(pteval(pte) + PAGE_SIZE). > > > > Architectures that implement things like flush_icache_page() and > > update_mmu_cache() may want to propose batched versions of those. > > That's alpha, csky, m68k, mips, nios2, parisc, sh, > > arm, loongarch, openrisc, powerpc, riscv, sparc and xtensa. > > Maintainers BCC'd, mailing lists CC'd. > > > > I'm happy to collect implementations and submit them as part of a v6. > > Please find below the riscv implementation for set_ptes: > > diff --git a/arch/riscv/include/asm/pgtable.h > b/arch/riscv/include/asm/pgtable.h > index ebee56d47003..10bf812776a4 100644 > --- a/arch/riscv/include/asm/pgtable.h > +++ b/arch/riscv/include/asm/pgtable.h > @@ -463,6 +463,20 @@ static inline void set_pte_at(struct mm_struct *mm, > __set_pte_at(mm, addr, ptep, pteval); > } > > +#define set_ptes set_ptes > +static inline void set_ptes(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep, pte_t pte, unsigned int nr) > +{ > + for (;;) { > + set_pte_at(mm, addr, ptep, pte); > + if (--nr == 0) > + break; > + ptep++; > + addr += PAGE_SIZE; > + pte = __pte(pte_val(pte) + (1 << _PAGE_PFN_SHIFT)); > + } > +} Given that this is the same code as the original version (surprise!), what about doing something like this in the generic code instead: #ifndef PTE_PAGE_STEP #define PTE_PAGE_STEP PAGE_SIZE #endif […] > + pte = __pte(pte_val(pte) + PTE_PAGE_STEP); The name of the define is an obvious candidate for bike-shedding, feel free to name it as you want. Or if that isn't sound enough maybe introduce something like: static inline pte_t set_ptes_next_pte(pte_t pte) { return __pte(pte_val(pte) + (1 << _PAGE_PFN_SHIFT)); } Greetings, Eike -- Rolf Eike Beer, emlix GmbH, http://www.emlix.com Fon +49 551 30664-0, Fax +49 551 30664-11 Gothaer Platz 3, 37083 Göttingen, Germany Sitz der Gesellschaft: Göttingen, Amtsgericht Göttingen HR B 3160 Geschäftsführung: Heike Jordan, Dr. Uwe Kracke – Ust-IdNr.: DE 205 198 055 emlix - smart embedded open source
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