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Shutemov" Cc: Yin Fengwei , linux-mm@kvack.org, david@redhat.com, dave.hansen@intel.com, tim.c.chen@intel.com, ying.huang@intel.com Subject: Re: [PATCH v5 2/5] mm: Add generic set_ptes() Message-ID: References: <20230207194937.122543-1-willy@infradead.org> <20230207194937.122543-3-willy@infradead.org> <20230208083848.craqlaft2xtmchwf@box.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230208083848.craqlaft2xtmchwf@box.shutemov.name> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 35F5640010 X-Stat-Signature: pqakohdj5o9uwdy1ydg4rm4hkt11goeg X-HE-Tag: 1675880095-163573 X-HE-Meta: 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 AwY+vZWk s+Pl1McvD5uXSv+TrDoCQ+ae0kw9zavcc67X/b1XM43lXNKpDJ0CTdAkh1YNYye134GOrd3hGlz99tppmrOBiBNlgZVrcy60XXF7V04DoWGZfSDx2IU4x/Q9c4tQ0jw9RcWakLFkaxCHspMpMLffel9xCpqMnlECbuaSg09heU6Xt7kMUbHHGcoqF5TpWZn+/YzoNOF38ZOQ8/iA= 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: On Wed, Feb 08, 2023 at 11:38:48AM +0300, Kirill A. Shutemov wrote: > > +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; > > Maybe do { ... } while (--nr); instead of the for()? Seems unnecessary to do the extra calculation to advance pte if we're not going to use it? > > + ptep++; > > + addr += PAGE_SIZE; > > + /* This works for x86. Check how PTEs are encoded */ > > + pte = __pte(pte_val(pte) + PAGE_SIZE); > > Looks like it deserves own helper. Something like > > pte = pte_next(pte); Maybe, but then it needs to be added to each arch, which I was trying to avoid. That said, I had another idea which I like better; more patches coming soon. Here's a sneak preview: +++ b/arch/x86/include/asm/pgtable.h @@ -1019,13 +1019,22 @@ static inline pud_t native_local_pudp_get_and_clear(pud_ t *pudp) return res; } -static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, - pte_t *ptep, pte_t pte) +static inline void set_ptes(struct mm_struct *mm, unsigned long addr, + pte_t *ptep, pte_t pte, unsigned int nr) { - page_table_check_ptes_set(mm, addr, ptep, pte, 1); - set_pte(ptep, pte); + page_table_check_ptes_set(mm, addr, ptep, pte, nr); + + for (;;) { + set_pte(ptep, pte); + if (--nr == 0) + break; + ptep++; + pte = __pte(pte_val(pte) + PAGE_SIZE); + } } +#define set_pte_at(mm, addr, ptep, pte) set_ptes(mm, addr, ptep, pte, 1) + static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp, pmd_t pmd) {