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b=eZTi5DzqiJVNB71Vp/b930nyv5R8JfheUpK2OUGe1zHqos2M5ckAZcuY0uXHL+/jk DSAAIg82wRixkfZy/2bZhUh+HAAZDTqK0vEmPAmIFDiAjRd96Xtx2ls9KkfsPID+oq yDy2IYeCxaPpeVO8BgDj9OlUi6pQCcf1/W0Z/BzTxB0WQ2VuG0AoR97Di3EEjiqSao 3UnxDWVvLXaRZ7uIyV+YaV+/A8m8fGzIkYCHF6NIaiQaNstSr2tbbe6ojUUSuralnr RFoqPo9+1Q3ynv4rcDpmUZeo8pqV2XWrpmPAIQtuFxMggirlmwSUAbODKTzgr4/vbo WjKfBlqSGs4UA== Date: Thu, 3 Apr 2025 09:24:04 +0300 From: Mike Rapoport To: David Woodhouse Cc: Andrew Morton , "Sauerwein, David" , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Marc Zyngier , Mark Rutland , Mike Rapoport , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 3/3] mm: Implement for_each_valid_pfn() for CONFIG_SPARSEMEM Message-ID: References: <20250402201841.3245371-1-dwmw2@infradead.org> <20250402201841.3245371-3-dwmw2@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250402201841.3245371-3-dwmw2@infradead.org> X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 32CB41A000B X-Stat-Signature: e4wjwnhrm9dtce3b969oiauhh77bkdhm X-Rspam-User: X-HE-Tag: 1743661453-710685 X-HE-Meta: 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 aIOSplrC S9/HDvWYmEo33D1SKcNT/ugVe39V2aNGl2t3UQD21AHZeEIEPGbgk6Yr0HTs5Ra1gwLu4D5tvSih7lh63vR7HgbulaFu9HVgFOoBK2ipOpC1VkET/V83WrZvtIc6YEDDYAexE/3RYRvfitEDmxZG2SIFhsT05ysoxTyq/GsvZbgI9wURa1q0fWrOx/6+5bDhgl8/LH9+U+qrJLycvIWfRZ0PV4Wo5az34gDet9qpR6dcFk7iOmi+dJ2B0cNtrTjNUxE3X1YJNae/MzMry8n643fpNP4YF+6Iauw+DB7+lD04NLlnc/12bEj1swuVnOGToztJ1zwGEyjKC4irmkfKoYubTQwngDu/1PY4h 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 Wed, Apr 02, 2025 at 09:18:41PM +0100, David Woodhouse wrote: > From: David Woodhouse > > Introduce a pfn_first_valid() helper which takes a pointer to the PFN and > updates it to point to the first valid PFN starting from that point, and > returns true if a valid PFN was found. > > This largely mirrors pfn_valid(), calling into a pfn_section_first_valid() > helper which is trivial for the !CONFIG_SPARSEMEM_VMEMMAP case, and in > the VMEMMAP case will skip to the next subsection as needed. > > Signed-off-by: David Woodhouse Reviewed-by: Mike Rapoport (Microsoft) with a small nit below > +static inline bool first_valid_pfn(unsigned long *p_pfn) > +{ > + unsigned long pfn = *p_pfn; > + unsigned long nr = pfn_to_section_nr(pfn); > + struct mem_section *ms; > + bool ret = false; > + > + ms = __pfn_to_section(pfn); > + > + rcu_read_lock_sched(); > + > + while (!ret && nr <= __highest_present_section_nr) { This could be just for(;;), we anyway break when ret becomes true or we get past last present section. > + if (valid_section(ms) && > + (early_section(ms) || pfn_section_first_valid(ms, &pfn))) { > + ret = true; > + break; > + } > + > + nr++; > + if (nr > __highest_present_section_nr) > + break; > + > + pfn = section_nr_to_pfn(nr); > + ms = __pfn_to_section(pfn); > + } > + > + rcu_read_unlock_sched(); > + > + *p_pfn = pfn; > + > + return ret; > +} > + > +#define for_each_valid_pfn(_pfn, _start_pfn, _end_pfn) \ > + for ((_pfn) = (_start_pfn); \ > + first_valid_pfn(&(_pfn)) && (_pfn) < (_end_pfn); \ > + (_pfn)++) > + > #endif > > static inline int pfn_in_present_section(unsigned long pfn) > -- > 2.49.0 > -- Sincerely yours, Mike.