From: Jan Kara <jack@suse.cz>
To: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>,
linux-nvdimm@lists.01.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 16/20] mm: Provide helper for finishing mkwrite faults
Date: Thu, 20 Oct 2016 10:48:45 +0200 [thread overview]
Message-ID: <20161020084845.GA22614@quack2.suse.cz> (raw)
In-Reply-To: <20161019172152.GC22463@linux.intel.com>
On Wed 19-10-16 11:21:52, Ross Zwisler wrote:
> On Wed, Oct 19, 2016 at 09:16:00AM +0200, Jan Kara wrote:
> > > > @@ -2315,26 +2335,17 @@ static int wp_page_shared(struct vm_fault *vmf)
> > > > put_page(vmf->page);
> > > > return tmp;
> > > > }
> > > > - /*
> > > > - * Since we dropped the lock we need to revalidate
> > > > - * the PTE as someone else may have changed it. If
> > > > - * they did, we just return, as we can count on the
> > > > - * MMU to tell us if they didn't also make it writable.
> > > > - */
> > > > - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
> > > > - vmf->address, &vmf->ptl);
> > > > - if (!pte_same(*vmf->pte, vmf->orig_pte)) {
> > > > + tmp = finish_mkwrite_fault(vmf);
> > > > + if (unlikely(!tmp || (tmp &
> > > > + (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
> > >
> > > The 'tmp' return from finish_mkwrite_fault() can only be 0 or VM_FAULT_WRITE.
> > > I think this test should just be
> > >
> > > if (unlikely(!tmp)) {
> >
> > Right, finish_mkwrite_fault() cannot currently throw other errors than
> > "retry needed" which is indicated by tmp == 0. However I'd prefer to keep
> > symmetry with finish_fault() handler which can throw other errors and
> > better be prepared to handle them from finish_mkwrite_fault() as well.
>
> Fair enough. You can add:
>
> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Thanks. Actually, your question made me have a harder look at return values
from finish_mkwrite_fault() and I've added one more commit switching the
return values so that finish_mkwrite_fault() returns 0 on success and
VM_FAULT_NOPAGE if PTE changed. That is less confusing and even more
consistent with what finish_fault() returns.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz>
To: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-nvdimm@lists.01.org,
Dan Williams <dan.j.williams@intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 16/20] mm: Provide helper for finishing mkwrite faults
Date: Thu, 20 Oct 2016 10:48:45 +0200 [thread overview]
Message-ID: <20161020084845.GA22614@quack2.suse.cz> (raw)
In-Reply-To: <20161019172152.GC22463@linux.intel.com>
On Wed 19-10-16 11:21:52, Ross Zwisler wrote:
> On Wed, Oct 19, 2016 at 09:16:00AM +0200, Jan Kara wrote:
> > > > @@ -2315,26 +2335,17 @@ static int wp_page_shared(struct vm_fault *vmf)
> > > > put_page(vmf->page);
> > > > return tmp;
> > > > }
> > > > - /*
> > > > - * Since we dropped the lock we need to revalidate
> > > > - * the PTE as someone else may have changed it. If
> > > > - * they did, we just return, as we can count on the
> > > > - * MMU to tell us if they didn't also make it writable.
> > > > - */
> > > > - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
> > > > - vmf->address, &vmf->ptl);
> > > > - if (!pte_same(*vmf->pte, vmf->orig_pte)) {
> > > > + tmp = finish_mkwrite_fault(vmf);
> > > > + if (unlikely(!tmp || (tmp &
> > > > + (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
> > >
> > > The 'tmp' return from finish_mkwrite_fault() can only be 0 or VM_FAULT_WRITE.
> > > I think this test should just be
> > >
> > > if (unlikely(!tmp)) {
> >
> > Right, finish_mkwrite_fault() cannot currently throw other errors than
> > "retry needed" which is indicated by tmp == 0. However I'd prefer to keep
> > symmetry with finish_fault() handler which can throw other errors and
> > better be prepared to handle them from finish_mkwrite_fault() as well.
>
> Fair enough. You can add:
>
> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Thanks. Actually, your question made me have a harder look at return values
from finish_mkwrite_fault() and I've added one more commit switching the
return values so that finish_mkwrite_fault() returns 0 on success and
VM_FAULT_NOPAGE if PTE changed. That is less confusing and even more
consistent with what finish_fault() returns.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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next prev parent reply other threads:[~2016-10-20 8:48 UTC|newest]
Thread overview: 126+ 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
[not found] ` <1474992504-20133-2-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30 9:07 ` Christoph Hellwig
2016-09-30 9:07 ` Christoph Hellwig
2016-10-14 18:02 ` Ross Zwisler
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
[not found] ` <1474992504-20133-3-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30 9:10 ` Christoph Hellwig
2016-09-30 9:10 ` Christoph Hellwig
2016-10-03 7:43 ` Jan Kara
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
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-14 18:42 ` Ross Zwisler
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
2016-09-27 16:08 ` Jan Kara
2016-10-14 19:05 ` Ross Zwisler
2016-10-14 19:05 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 05/20] mm: Trim __do_fault() arguments Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-14 20:31 ` Ross Zwisler
2016-10-17 9:04 ` Jan Kara
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
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-14 21:04 ` Ross Zwisler
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
2016-10-17 16:45 ` Ross Zwisler
2016-10-18 10:13 ` Jan Kara
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
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` 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 17:38 ` Ross Zwisler
2016-10-17 17:40 ` 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
2016-10-17 19:29 ` Ross Zwisler
2016-10-18 10:32 ` Jan Kara
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
2016-10-17 19:40 ` Ross Zwisler
2016-10-18 10:37 ` Jan Kara
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
2016-09-27 16:08 ` Jan Kara
2016-10-17 22:08 ` Ross Zwisler
2016-10-17 22:08 ` Ross Zwisler
2016-10-18 10:50 ` Jan Kara
2016-10-18 17:32 ` Ross Zwisler
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
2016-10-17 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
2016-10-18 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
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` 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
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-18 18:35 ` Ross Zwisler
2016-10-18 18:35 ` Ross Zwisler
2016-10-19 7:16 ` Jan Kara
2016-10-19 7:16 ` Jan Kara
2016-10-19 17:21 ` Ross Zwisler
2016-10-19 17:21 ` Ross Zwisler
2016-10-20 8:48 ` Jan Kara [this message]
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
2016-10-18 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 7:19 ` Jan Kara
2016-10-19 18:25 ` Ross Zwisler
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
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-18 19:53 ` Ross Zwisler
2016-10-18 19:53 ` Ross Zwisler
2016-10-19 7:25 ` Jan Kara
2016-10-19 7:25 ` Jan Kara
2016-10-19 17:25 ` Ross Zwisler
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
2016-09-27 16:08 ` Jan Kara
2016-10-18 22:12 ` Ross Zwisler
2016-10-18 22:12 ` Ross Zwisler
2016-10-19 7:30 ` Jan Kara
2016-10-19 7:30 ` Jan Kara
2016-10-19 16:38 ` Ross Zwisler
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 8:15 ` Jan Kara
2016-10-03 9:32 ` Christoph Hellwig
2016-10-03 9:32 ` Christoph Hellwig
2016-10-03 11:13 ` Jan Kara
[not found] ` <20161003111358.GQ6457-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2016-10-13 20:34 ` Ross Zwisler
2016-10-13 20:34 ` Ross Zwisler
2016-10-17 8:47 ` Jan Kara
2016-10-17 8:47 ` Jan Kara
[not found] ` <20161017084732.GD3359-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2016-10-17 18:59 ` Ross Zwisler
2016-10-17 18:59 ` Ross Zwisler
2016-10-18 9:49 ` Jan Kara
2016-10-18 9:49 ` Jan Kara
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