From: Jan Kara <jack@suse.cz> To: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz>, Matthew Wilcox <willy@infradead.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Boaz Harrosh <openosd@gmail.com>, stable <stable@vger.kernel.org>, Robert Barror <robert.barror@intel.com>, Seema Pandit <seema.pandit@intel.com>, linux-nvdimm <linux-nvdimm@lists.01.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Subject: Re: [PATCH] dax: Fix missed PMD wakeups Date: Mon, 29 Jul 2019 14:02:28 +0200 Message-ID: <20190729120228.GC17833@quack2.suse.cz> (raw) In-Reply-To: <CAPcyv4hA+44EHpGN9F5eQD5Y_AuyPTKmovNWvccAFGhF_O2JMg@mail.gmail.com> [-- Attachment #1: Type: text/plain, Size: 1574 bytes --] On Tue 16-07-19 20:39:46, Dan Williams wrote: > On Fri, Jul 12, 2019 at 2:14 AM Jan Kara <jack@suse.cz> wrote: > > > > On Thu 11-07-19 08:25:50, Matthew Wilcox wrote: > > > On Thu, Jul 11, 2019 at 07:13:50AM -0700, Matthew Wilcox wrote: > > > > However, the XA_RETRY_ENTRY might be a good choice. It doesn't normally > > > > appear in an XArray (it may appear if you're looking at a deleted node, > > > > but since we're holding the lock, we can't see deleted nodes). > > > > > ... > > > > > @@ -254,7 +267,7 @@ static void wait_entry_unlocked(struct xa_state *xas, void *entry) > > > static void put_unlocked_entry(struct xa_state *xas, void *entry) > > > { > > > /* If we were the only waiter woken, wake the next one */ > > > - if (entry) > > > + if (entry && dax_is_conflict(entry)) > > > > This should be !dax_is_conflict(entry)... > > > > > dax_wake_entry(xas, entry, false); > > > } > > > > Otherwise the patch looks good to me so feel free to add: > > > > Reviewed-by: Jan Kara <jack@suse.cz> > > Looks good, and passes the test case. Now pushed out to > libnvdimm-for-next for v5.3 inclusion: > > https://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm.git/commit/?h=libnvdimm-for-next&id=23c84eb7837514e16d79ed6d849b13745e0ce688 Thanks for picking up the patch but you didn't apply the fix I've mentioned above. So put_unlocked_entry() is not waking up anybody anymore... Since this got already to Linus' tree, I guess a separate fixup patch is needed (attached). Honza -- Jan Kara <jack@suse.com> SUSE Labs, CR [-- Attachment #2: 0001-dax-Fix-missed-wakup-in-put_unlocked_entry.patch --] [-- Type: text/x-patch, Size: 1229 bytes --] From 950204f7dfdb06198f40820be4d33ce824508f11 Mon Sep 17 00:00:00 2001 From: Jan Kara <jack@suse.cz> Date: Mon, 29 Jul 2019 13:57:49 +0200 Subject: [PATCH] dax: Fix missed wakup in put_unlocked_entry() The condition checking whether put_unlocked_entry() needs to wake up following waiter got broken by commit 23c84eb78375 ("dax: Fix missed wakeup with PMD faults"). We need to wake the waiter whenever the passed entry is valid (i.e., non-NULL and not special conflict entry). This could lead to processes never being woken up when waiting for entry lock. Fix the condition. CC: stable@vger.kernel.org Fixes: 23c84eb78375 ("dax: Fix missed wakeup with PMD faults") Signed-off-by: Jan Kara <jack@suse.cz> --- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index a237141d8787..b64964ef44f6 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -266,7 +266,7 @@ static void wait_entry_unlocked(struct xa_state *xas, void *entry) static void put_unlocked_entry(struct xa_state *xas, void *entry) { /* If we were the only waiter woken, wake the next one */ - if (entry && dax_is_conflict(entry)) + if (entry && !dax_is_conflict(entry)) dax_wake_entry(xas, entry, false); } -- 2.16.4
next prev parent reply index Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-03 7:24 Dan Williams 2019-07-03 12:17 ` Matthew Wilcox 2019-07-03 17:01 ` Dan Williams 2019-07-03 19:53 ` Matthew Wilcox 2019-07-03 21:28 ` Dan Williams 2019-07-04 3:27 ` Matthew Wilcox 2019-07-04 13:00 ` Boaz Harrosh 2019-07-04 13:58 ` Matthew Wilcox 2019-07-04 14:32 ` Boaz Harrosh 2019-07-04 16:54 ` Jan Kara 2019-07-04 19:14 ` Matthew Wilcox 2019-07-04 23:27 ` Dan Williams 2019-07-05 19:10 ` Matthew Wilcox 2019-07-05 20:47 ` Dan Williams 2019-07-10 19:02 ` Jan Kara 2019-07-10 20:15 ` Matthew Wilcox 2019-07-10 20:26 ` Jan Kara 2019-07-11 14:13 ` Matthew Wilcox 2019-07-11 15:25 ` Matthew Wilcox 2019-07-11 15:41 ` Jan Kara 2019-07-17 3:39 ` Dan Williams 2019-07-29 12:02 ` Jan Kara [this message] 2019-07-29 15:18 ` Dan Williams 2019-07-11 3:08 ` Matthew Wilcox 2019-07-11 7:48 ` Jan Kara 2019-07-11 13:28 ` Matthew Wilcox 2019-07-11 3:35 ` Matthew Wilcox 2019-07-11 8:06 ` Jan Kara
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