On Tue, Jan 23, 2024 at 10:36:14AM +0800, Zhihao Cheng wrote: > 在 2024/1/22 22:40, Matthew Wilcox 写道: > > On Mon, Jan 22, 2024 at 03:22:45PM +0800, Zhihao Cheng wrote: > > > 在 2024/1/21 7:08, Matthew Wilcox (Oracle) 写道: > > > > Page cache reads are lockless, so setting the freshly allocated page > > > > uptodate before we've overwritten it with the data it's supposed to have > > > > in it will allow a simultaneous reader to see old data. Move the call > > > > to SetPageUptodate into ubifs_write_end(), which is after we copied the > > > > new data into the page. > > > > > > This solution looks good to me, and I think 'SetPageUptodate' should be > > > removed from write_begin_slow(slow path) too. > > > > I didn't bother because we have just read into the page so it is > > uptodate. A racing read will see the data from before the write, but > > that's an acceptable ordering of events. > > . > > > > I can't find where the page is read and set uptodate. I think the > uninitialized data can be found in following path: You're right; thanks. I'd misread the code. I'll send a new version in a few hours.
