From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 00DE921A07A92 for ; Mon, 26 Nov 2018 04:22:25 -0800 (PST) Date: Mon, 26 Nov 2018 04:22:23 -0800 From: Matthew Wilcox Subject: Re: FAILED: patch "[PATCH] dax: Avoid losing wakeup in dax_lock_mapping_entry" failed to apply to 4.19-stable tree Message-ID: <20181126122223.GG3065@bombadil.infradead.org> References: <154322882028207@kroah.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <154322882028207@kroah.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: gregkh@linuxfoundation.org Cc: stable@vger.kernel.org, linux-nvdimm@lists.01.org List-ID: On Mon, Nov 26, 2018 at 11:40:20AM +0100, gregkh@linuxfoundation.org wrote: > > The patch below does not apply to the 4.19-stable tree. > If someone wants it applied there, or to any other stable or longterm > tree, then please email the backport, including the original git commit > id to . The fix for 4.19 is rather more complex because we don't have the right information in the right places. Dan, does this look right to you? diff --git a/fs/dax.c b/fs/dax.c index 0fb270f0a0ef6..b8dd66f1951a6 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -227,7 +227,9 @@ static inline void *unlock_slot(struct address_space *mapping, void **slot) * Must be called with the i_pages lock held. */ static void *__get_unlocked_mapping_entry(struct address_space *mapping, - pgoff_t index, void ***slotp, bool (*wait_fn)(void)) + pgoff_t index, void ***slotp, + bool (*wait_fn)(struct address_space *mapping, + pgoff_t index, void *entry)) { void *entry, **slot; struct wait_exceptional_entry_queue ewait; @@ -253,7 +255,7 @@ static void *__get_unlocked_mapping_entry(struct address_space *mapping, prepare_to_wait_exclusive(wq, &ewait.wait, TASK_UNINTERRUPTIBLE); xa_unlock_irq(&mapping->i_pages); - revalidate = wait_fn(); + revalidate = wait_fn(mapping, index, entry); finish_wait(wq, &ewait.wait); xa_lock_irq(&mapping->i_pages); if (revalidate) @@ -261,7 +263,8 @@ static void *__get_unlocked_mapping_entry(struct address_space *mapping, } } -static bool entry_wait(void) +static bool entry_wait(struct address_space *mapping, unsigned long index, + void *entry) { schedule(); /* @@ -393,12 +396,18 @@ static struct page *dax_busy_page(void *entry) return NULL; } -static bool entry_wait_revalidate(void) +static bool entry_wait_revalidate(struct address_space *mapping, + unsigned long index, void *entry) { rcu_read_unlock(); schedule(); rcu_read_lock(); + /* + * We're not going to do anything with this entry; wake the next + * task in line + */ + put_unlocked_mapping_entry(mapping, index, entry); /* * Tell __get_unlocked_mapping_entry() to take a break, we need * to revalidate page->mapping after dropping locks > ------------------ original commit in Linus's tree ------------------ > > >From 25bbe21bf427a81b8e3ccd480ea0e1d940256156 Mon Sep 17 00:00:00 2001 > From: Matthew Wilcox > Date: Fri, 16 Nov 2018 15:50:02 -0500 > Subject: [PATCH] dax: Avoid losing wakeup in dax_lock_mapping_entry > > After calling get_unlocked_entry(), you have to call > put_unlocked_entry() to avoid subsequent waiters losing wakeups. > > Fixes: c2a7d2a11552 ("filesystem-dax: Introduce dax_lock_mapping_entry()") > Cc: stable@vger.kernel.org > Signed-off-by: Matthew Wilcox > > diff --git a/fs/dax.c b/fs/dax.c > index cf2394e2bf4b..9bcce89ea18e 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -391,6 +391,7 @@ bool dax_lock_mapping_entry(struct page *page) > rcu_read_unlock(); > entry = get_unlocked_entry(&xas); > xas_unlock_irq(&xas); > + put_unlocked_entry(&xas, entry); > rcu_read_lock(); > continue; > } > _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm