From: Matthew Wilcox <willy@infradead.org>
To: Zhihao Cheng <chengzhihao1@huawei.com>
Cc: Richard Weinberger <richard@nod.at>,
linux-mtd@lists.infradead.org, stable@vger.kernel.org
Subject: Re: [PATCH 01/15] ubifs: Set page uptodate in the correct place
Date: Wed, 24 Jan 2024 05:01:59 +0000 [thread overview]
Message-ID: <ZbCZx10_Yj-TlSdM@casper.infradead.org> (raw)
In-Reply-To: <f96965c0-8464-c12c-7e5c-95ba74d10b7d@huawei.com>
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.
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next prev parent reply other threads:[~2024-01-24 5:02 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-20 23:08 [PATCH 00/15] ubifs folio conversion Matthew Wilcox (Oracle)
2024-01-20 23:08 ` [PATCH 01/15] ubifs: Set page uptodate in the correct place Matthew Wilcox (Oracle)
2024-01-22 7:22 ` Zhihao Cheng
2024-01-22 14:40 ` Matthew Wilcox
2024-01-23 2:36 ` Zhihao Cheng
2024-01-24 5:01 ` Matthew Wilcox [this message]
2024-01-20 23:08 ` [PATCH 02/15] ubifs: Convert from writepage to writepages Matthew Wilcox (Oracle)
2024-01-22 11:31 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 03/15] ubifs: Convert ubifs_writepage to use a folio Matthew Wilcox (Oracle)
2024-01-22 9:27 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 04/15] ubifs: Use a folio in do_truncation() Matthew Wilcox (Oracle)
2024-01-22 9:31 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 05/15] ubifs: Convert do_writepage() to take a folio Matthew Wilcox (Oracle)
2024-01-22 11:31 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 06/15] ubifs: Convert ubifs_vm_page_mkwrite() to use " Matthew Wilcox (Oracle)
2024-01-22 11:38 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 07/15] ubifs: Convert write_begin_slow() " Matthew Wilcox (Oracle)
2024-01-20 23:08 ` [PATCH 08/15] ubifs: Convert ubifs_write_begin() " Matthew Wilcox (Oracle)
2024-01-22 11:51 ` Zhihao Cheng
2024-01-22 14:43 ` Matthew Wilcox
2024-01-23 2:15 ` Zhihao Cheng
2024-01-23 3:07 ` Matthew Wilcox
2024-01-23 4:27 ` Zhihao Cheng
2024-01-23 4:27 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 09/15] ubifs: Convert ubifs_write_end() " Matthew Wilcox (Oracle)
2024-01-23 4:39 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 10/15] ubifs: Convert do_readpage() to take " Matthew Wilcox (Oracle)
2024-01-22 12:09 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 11/15] ubifs: Convert allocate_budget() to work on " Matthew Wilcox (Oracle)
2024-01-22 11:52 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 12/15] ubifs: Convert cancel_budget() to take " Matthew Wilcox (Oracle)
2024-01-22 12:14 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 13/15] ubifs: Pass a folio into ubifs_bulk_read() and ubifs_do_bulk_read() Matthew Wilcox (Oracle)
2024-01-22 12:15 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 14/15] ubifs: Use a folio in ubifs_do_bulk_read() Matthew Wilcox (Oracle)
2024-01-22 12:17 ` Zhihao Cheng
2024-01-20 23:08 ` [PATCH 15/15] ubifs: Convert populate_page() to take a folio Matthew Wilcox (Oracle)
2024-01-22 12:22 ` Zhihao Cheng
2024-01-23 7:33 ` [PATCH 00/15] ubifs folio conversion Richard Weinberger
2024-01-24 5:01 ` Matthew Wilcox
2024-01-25 2:05 ` Zhihao Cheng
2024-02-15 20:46 ` Matthew Wilcox
2024-02-15 20:54 ` Richard Weinberger
2024-02-25 22:13 ` Richard Weinberger
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