From: Jason Gunthorpe <jgg@nvidia.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
akpm@linux-foundation.org, Matthew Wilcox <willy@infradead.org>,
Jan Kara <jack@suse.cz>, "Darrick J. Wong" <djwong@kernel.org>,
Christoph Hellwig <hch@lst.de>,
John Hubbard <jhubbard@nvidia.com>,
linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev,
linux-xfs@vger.kernel.org, linux-mm@kvack.org,
linux-ext4@vger.kernel.org
Subject: Re: [PATCH v2 10/18] fsdax: Manage pgmap references at entry insertion and deletion
Date: Tue, 27 Sep 2022 09:56:06 -0300 [thread overview]
Message-ID: <YzLy5jJOF0jdlrJK@nvidia.com> (raw)
In-Reply-To: <8735cdl4pk.fsf@nvdebian.thelocal>
On Tue, Sep 27, 2022 at 04:07:05PM +1000, Alistair Popple wrote:
> That sounds good to me at least. I just noticed we introduced this exact
> bug for device private/coherent pages when making their refcounts zero
> based. Nothing currently takes pgmap->ref when a private/coherent page
> is mapped. Therefore memunmap_pages() will complete and pgmap destroyed
> while pgmap pages are still mapped.
To kind of summarize this thread
Either we should get the pgmap reference during the refcount = 1 flow,
and put it during page_free()
Or we should have the pgmap destroy sweep all the pages and wait for
them to become ref == 0
I don't think we should have pgmap references randomly strewn all over
the place. A positive refcount on the page alone must be enough to
prove that the struct page exists and the pgmap is not destroyed.
Every driver using pgmap needs something liek this, so I'd prefer it
be in the pgmap code..
Jason
next prev parent reply other threads:[~2022-09-27 12:56 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 3:35 [PATCH v2 00/18] Fix the DAX-gup mistake Dan Williams
2022-09-16 3:35 ` [PATCH v2 01/18] fsdax: Wait on @page not @page->_refcount Dan Williams
2022-09-20 14:30 ` Jason Gunthorpe
2022-09-16 3:35 ` [PATCH v2 02/18] fsdax: Use dax_page_idle() to document DAX busy page checking Dan Williams
2022-09-20 14:31 ` Jason Gunthorpe
2022-09-16 3:35 ` [PATCH v2 03/18] fsdax: Include unmapped inodes for page-idle detection Dan Williams
2022-09-16 3:35 ` [PATCH v2 04/18] ext4: Add ext4_break_layouts() to the inode eviction path Dan Williams
2022-09-16 3:35 ` [PATCH v2 05/18] xfs: Add xfs_break_layouts() " Dan Williams
[not found] ` <20220918225731.GG3600936@dread.disaster.area>
2022-09-19 16:11 ` Dan Williams
[not found] ` <20220919212959.GL3600936@dread.disaster.area>
2022-09-20 16:44 ` Dan Williams
[not found] ` <20220921221416.GT3600936@dread.disaster.area>
2022-09-21 22:28 ` Jason Gunthorpe
[not found] ` <20220923001846.GX3600936@dread.disaster.area>
2022-09-23 0:41 ` Dan Williams
[not found] ` <20220923021012.GZ3600936@dread.disaster.area>
2022-09-23 9:38 ` Jan Kara
2022-09-23 23:06 ` Dan Williams
[not found] ` <20220925235407.GA3600936@dread.disaster.area>
2022-09-26 14:10 ` Jan Kara
2022-09-29 23:33 ` Dan Williams
2022-09-30 13:41 ` Jan Kara
2022-09-30 17:56 ` Dan Williams
2022-09-30 18:06 ` Jason Gunthorpe
2022-09-30 18:46 ` Dan Williams
2022-10-03 7:55 ` Jan Kara
2022-09-23 12:39 ` Jason Gunthorpe
[not found] ` <20220926003430.GB3600936@dread.disaster.area>
2022-09-26 13:04 ` Jason Gunthorpe
2022-09-22 0:02 ` Dan Williams
2022-09-22 0:10 ` Jason Gunthorpe
2022-09-16 3:35 ` [PATCH v2 06/18] fsdax: Rework dax_layout_busy_page() to dax_zap_mappings() Dan Williams
2022-09-16 3:35 ` [PATCH v2 07/18] fsdax: Update dax_insert_entry() calling convention to return an error Dan Williams
2022-09-16 3:35 ` [PATCH v2 08/18] fsdax: Cleanup dax_associate_entry() Dan Williams
2022-09-16 3:36 ` [PATCH v2 09/18] fsdax: Rework dax_insert_entry() calling convention Dan Williams
2022-09-16 3:36 ` [PATCH v2 10/18] fsdax: Manage pgmap references at entry insertion and deletion Dan Williams
2022-09-21 14:03 ` Jason Gunthorpe
2022-09-21 15:18 ` Dan Williams
2022-09-21 21:38 ` Dan Williams
2022-09-21 22:07 ` Jason Gunthorpe
2022-09-22 0:14 ` Dan Williams
2022-09-22 0:25 ` Jason Gunthorpe
2022-09-22 2:17 ` Dan Williams
2022-09-22 17:55 ` Jason Gunthorpe
2022-09-22 21:54 ` Dan Williams
2022-09-23 1:36 ` Dave Chinner
2022-09-23 2:01 ` Dan Williams
2022-09-23 13:24 ` Jason Gunthorpe
2022-09-23 16:29 ` Dan Williams
2022-09-23 17:42 ` Jason Gunthorpe
2022-09-23 19:03 ` Dan Williams
2022-09-23 19:23 ` Jason Gunthorpe
2022-09-27 6:07 ` Alistair Popple
2022-09-27 12:56 ` Jason Gunthorpe [this message]
2022-09-16 3:36 ` [PATCH v2 11/18] devdax: Minor warning fixups Dan Williams
2022-09-16 3:36 ` [PATCH v2 12/18] devdax: Move address_space helpers to the DAX core Dan Williams
2022-09-27 6:20 ` Alistair Popple
2022-09-29 22:38 ` Dan Williams
2022-09-16 3:36 ` [PATCH v2 13/18] dax: Prep mapping helpers for compound pages Dan Williams
2022-09-21 14:06 ` Jason Gunthorpe
2022-09-21 15:19 ` Dan Williams
2022-09-16 3:36 ` [PATCH v2 14/18] devdax: add PUD support to the DAX mapping infrastructure Dan Williams
2022-09-16 3:36 ` [PATCH v2 15/18] devdax: Use dax_insert_entry() + dax_delete_mapping_entry() Dan Williams
2022-09-21 14:10 ` Jason Gunthorpe
2022-09-21 15:48 ` Dan Williams
2022-09-21 22:23 ` Jason Gunthorpe
2022-09-22 0:15 ` Dan Williams
2022-09-16 3:36 ` [PATCH v2 16/18] mm/memremap_pages: Support initializing pages to a zero reference count Dan Williams
2022-09-21 15:24 ` Jason Gunthorpe
2022-09-21 23:45 ` Dan Williams
2022-09-22 0:03 ` Alistair Popple
2022-09-22 0:04 ` Jason Gunthorpe
2022-09-22 0:34 ` Dan Williams
2022-09-22 1:36 ` Alistair Popple
2022-09-22 2:34 ` Dan Williams
2022-09-26 6:17 ` Alistair Popple
2022-09-22 0:13 ` John Hubbard
2022-09-16 3:36 ` [PATCH v2 17/18] fsdax: Delete put_devmap_managed_page_refs() Dan Williams
2022-09-16 3:36 ` [PATCH v2 18/18] mm/gup: Drop DAX pgmap accounting Dan Williams
2022-09-20 14:29 ` [PATCH v2 00/18] Fix the DAX-gup mistake Jason Gunthorpe
2022-09-20 16:50 ` Dan Williams
2022-11-09 0:20 ` Andrew Morton
2022-11-09 11:38 ` Jan Kara
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