linux-kernel - Re: [PATCH -next v1 3/3] kernel/events/uprobes: uprobe_write

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Message-ID: <bf8ac5ba-74ca-4ddb-bf28-1c2834907146@redhat.com>
Date: Wed, 5 Mar 2025 20:37:02 +0100
From: David Hildenbrand <david@...hat.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 linux-arm-kernel@...ts.infradead.org, linux-trace-kernel@...r.kernel.org,
 linux-perf-users@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
 Russell King <linux@...linux.org.uk>, Masami Hiramatsu
 <mhiramat@...nel.org>, Oleg Nesterov <oleg@...hat.com>,
 Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Adrian Hunter <adrian.hunter@...el.com>,
 "Liang, Kan" <kan.liang@...ux.intel.com>,
 Tong Tiangen <tongtiangen@...wei.com>
Subject: Re: [PATCH -next v1 3/3] kernel/events/uprobes: uprobe_write_opcode()
 rewrite

On 05.03.25 20:30, Matthew Wilcox wrote:
> On Tue, Mar 04, 2025 at 04:48:46PM +0100, David Hildenbrand wrote:
>> +static bool orig_page_is_identical(struct vm_area_struct *vma,
>> +		unsigned long vaddr, struct page *page, bool *pmd_mappable)
>> +{
>> +	const pgoff_t index = vaddr_to_offset(vma, vaddr) >> PAGE_SHIFT;
>> +	struct page *orig_page = find_get_page(vma->vm_file->f_inode->i_mapping,
>> +					       index);
>> +	struct folio *orig_folio;
>> +	bool identical;
>> +
>> +	if (!orig_page)
>> +		return false;
>> +	orig_folio = page_folio(orig_page);
> 
> I'd rather write this as:
> 
> 	struct folio *orig_folio = filemap_get_folio(vma->vm_file->f_mapping,
> 			index);
> 	struct page *orig_page;
> 
> 	if (IS_ERR(orig_folio))
> 		return false;
> 	orig_page = folio_file_page(folio, index);
> 

Willy, you read my mind. I was staring at that code and thought "there 
must be an easier way using pages", and folio_file_page() was the 
missing piece.

Thanks!

-- 
Cheers,

David / dhildenb