From: Jan Kara <jack@suse.cz>
To: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@infradead.org>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-nvdimm@ml01.01.org, Dan Williams <dan.j.williams@intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 0/20 v3] dax: Clear dirty bits after flushing caches
Date: Mon, 17 Oct 2016 10:47:32 +0200 [thread overview]
Message-ID: <20161017084732.GD3359@quack2.suse.cz> (raw)
In-Reply-To: <20161013203434.GD26922@linux.intel.com>
On Thu 13-10-16 14:34:34, Ross Zwisler wrote:
> On Mon, Oct 03, 2016 at 01:13:58PM +0200, Jan Kara wrote:
> > On Mon 03-10-16 02:32:48, Christoph Hellwig wrote:
> > > On Mon, Oct 03, 2016 at 10:15:49AM +0200, Jan Kara wrote:
> > > > Yeah, so DAX path is special because it installs its own PTE directly from
> > > > the fault handler which we don't do in any other case (only driver fault
> > > > handlers commonly do this but those generally don't care about
> > > > ->page_mkwrite or file mappings for that matter).
> > > >
> > > > I don't say there are no simplifications or unifications possible, but I'd
> > > > prefer to leave them for a bit later once the current churn with ongoing
> > > > work somewhat settles...
> > >
> > > Allright, let's keep it simple for now. Being said this series clearly
> > > is 4.9 material, but any chance to get a respin of the invalidate_pages
> >
> > Agreed (actually 4.10).
> >
> > > series as that might still be 4.8 material?
> >
> > The problem with invalidate_pages series is that it depends on the ability
> > to clear the dirty bits in the radix tree of DAX mappings (i.e. the first
> > series). Otherwise radix tree entries that get once dirty can never be safely
> > evicted, invalidate_inode_pages2_range() will keep returning EBUSY and
> > callers get confused (I've tried that few weeks ago).
> >
> > If I dropped patch 5/6 for 4.9 merge (i.e., we would still happily discard
> > dirty radix tree entries from invalidate_inode_pages2_range()), things
> > would run fine, just fsync() may miss to flush caches for some pages. I'm
> > not sure that's much better than current status quo though. Thoughts?
>
> I'm not sure if I'm understanding this correctly, but if you're saying
> that we might end up in a case where fsync()/msync() would fail to
> properly flush pages that are/should be dirty, I think this is a no-go.
> That could result in data corruption if a user calls fsync(), thinks
> they've achieved a synchronization point (updating other metadata or
> whatever), then via power loss they lose data they had flushed via that
> previous fsync() because it was still in the CPU cache and never really
> made it out to media.
I know and actually current code is buggy in that way as well and this
patch set is fixing it. But I was arguing that only applying part of the
fixes so that the main problem remains unfixed would not be very beneficial
anyway.
This week I plan to rebase both series on top of rc1 + your THP patches so
that we can move on with merging the stuff.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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next prev parent reply other threads:[~2016-10-17 8:47 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 16:08 [PATCH 0/20 v3] dax: Clear dirty bits after flushing caches Jan Kara
2016-09-27 16:08 ` [PATCH 01/20] mm: Change type of vmf->virtual_address Jan Kara
2016-09-30 9:07 ` Christoph Hellwig
2016-10-14 18:02 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 02/20] mm: Join struct fault_env and vm_fault Jan Kara
2016-09-30 9:10 ` Christoph Hellwig
2016-10-03 7:43 ` Jan Kara
2016-09-27 16:08 ` [PATCH 03/20] mm: Use pgoff in struct vm_fault instead of passing it separately Jan Kara
2016-10-14 18:42 ` Ross Zwisler
2016-10-17 9:01 ` Jan Kara
2016-09-27 16:08 ` [PATCH 04/20] mm: Use passed vm_fault structure in __do_fault() Jan Kara
2016-10-14 19:05 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 05/20] mm: Trim __do_fault() arguments Jan Kara
2016-10-14 20:31 ` Ross Zwisler
2016-10-17 9:04 ` Jan Kara
2016-09-27 16:08 ` [PATCH 06/20] mm: Use pass vm_fault structure for in wp_pfn_shared() Jan Kara
2016-10-14 21:04 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 07/20] mm: Add orig_pte field into vm_fault Jan Kara
2016-10-17 16:45 ` Ross Zwisler
2016-10-18 10:13 ` Jan Kara
2016-09-27 16:08 ` [PATCH 08/20] mm: Allow full handling of COW faults in ->fault handlers Jan Kara
2016-10-17 16:50 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 09/20] mm: Factor out functionality to finish page faults Jan Kara
2016-10-17 17:38 ` Ross Zwisler
2016-10-17 17:40 ` Ross Zwisler
2016-10-18 9:44 ` Jan Kara
2016-09-27 16:08 ` [PATCH 10/20] mm: Move handling of COW faults into DAX code Jan Kara
2016-10-17 19:29 ` Ross Zwisler
2016-10-18 10:32 ` Jan Kara
2016-09-27 16:08 ` [PATCH 11/20] mm: Remove unnecessary vma->vm_ops check Jan Kara
2016-10-17 19:40 ` Ross Zwisler
2016-10-18 10:37 ` Jan Kara
2016-09-27 16:08 ` [PATCH 12/20] mm: Factor out common parts of write fault handling Jan Kara
2016-10-17 22:08 ` Ross Zwisler
2016-10-18 10:50 ` Jan Kara
2016-10-18 17:32 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 13/20] mm: Pass vm_fault structure into do_page_mkwrite() Jan Kara
2016-10-17 22:29 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 14/20] mm: Use vmf->page during WP faults Jan Kara
2016-10-18 17:56 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 15/20] mm: Move part of wp_page_reuse() into the single call site Jan Kara
2016-10-18 17:59 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 16/20] mm: Provide helper for finishing mkwrite faults Jan Kara
2016-10-18 18:35 ` Ross Zwisler
2016-10-19 7:16 ` Jan Kara
2016-10-19 17:21 ` Ross Zwisler
2016-10-20 8:48 ` Jan Kara
2016-09-27 16:08 ` [PATCH 17/20] mm: Export follow_pte() Jan Kara
2016-10-18 18:37 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 18/20] dax: Make cache flushing protected by entry lock Jan Kara
2016-10-18 19:20 ` Ross Zwisler
2016-10-19 7:19 ` Jan Kara
2016-10-19 18:25 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 19/20] dax: Protect PTE modification on WP fault by radix tree " Jan Kara
2016-10-18 19:53 ` Ross Zwisler
2016-10-19 7:25 ` Jan Kara
2016-10-19 17:25 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 20/20] dax: Clear dirty entry tags on cache flush Jan Kara
2016-10-18 22:12 ` Ross Zwisler
2016-10-19 7:30 ` Jan Kara
2016-10-19 16:38 ` Ross Zwisler
2016-09-30 9:14 ` [PATCH 0/20 v3] dax: Clear dirty bits after flushing caches Christoph Hellwig
2016-10-03 7:59 ` Jan Kara
2016-10-03 8:03 ` Christoph Hellwig
2016-10-03 8:15 ` Jan Kara
2016-10-03 9:32 ` Christoph Hellwig
2016-10-03 11:13 ` Jan Kara
2016-10-13 20:34 ` Ross Zwisler
2016-10-17 8:47 ` Jan Kara [this message]
2016-10-17 18:59 ` Ross Zwisler
2016-10-18 9:49 ` Jan Kara
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