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Peter Anvin" , Linus Torvalds Subject: Re: [PATCH v1] x86/mm/pat: (un)track_pfn_copy() fix + improvements Message-ID: References: <20250404124931.2255618-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250404124931.2255618-1-david@redhat.com> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 62D9EA0005 X-Stat-Signature: f5ehgmwt75dr7bewgnqwujowttbkr6je X-HE-Tag: 1743960513-567576 X-HE-Meta: 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 OB8igxDY //Dmzm2MKzkVsV/CEDebSOWjSOcUtUflbKWDuDWr4Olp0WQnr8kpJlUBqqTYag4/Ben/QG8yydmBDGVRTErMXD7VCx9826SnP5/xVCBFuyUuHAnEKdpYFvQxsT7+WZJiyBGmrY6O2yPWMewyN9j1pREMGoZwZltuPm0rxzYbHZeP0eNWqCoYhy00sKbTmEX38h+GwbmwfWLtPFqen9ZepzXbO1HgC71Rl4xCj2htI5ku7WzqvQNTM5n2Rg8MObZjrKVPE0UT3S4AWoHvX3Au0m8gLUg/m+XEuiJSV 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: * David Hildenbrand wrote: > We got a late smatch warning and some additional review feedback. > > smatch warnings: > mm/memory.c:1428 copy_page_range() error: uninitialized symbol 'pfn'. > - if (!(src_vma->vm_flags & VM_PAT)) > + if (!(src_vma->vm_flags & VM_PAT)) { > + *pfn = 0; > return 0; > + } > static inline int track_pfn_copy(struct vm_area_struct *dst_vma, > struct vm_area_struct *src_vma, unsigned long *pfn) > { > + *pfn = 0; > return 0; > } That's way too ugly. There's nothing wrong with not touching 'pfn' in the error path: in fact it's pretty standard API where output pointers may not get set on errors. If Smatch has a problem with it, Smatch should be fixed, or the false positive warning should be worked around by initializing 'pfn' in the callers. Thanks, Ingo