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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s2Awc-0000000H4FY-3319; Wed, 01 May 2024 14:28:26 +0000 Date: Wed, 1 May 2024 15:28:26 +0100 From: Matthew Wilcox To: Luis Chamberlain Cc: Zi Yan , Andrew Morton , Vlastimil Babka , Sean Christopherson , "Pankaj Raghav (Samsung)" , djwong@kernel.org, brauner@kernel.org, david@fromorbit.com, chandan.babu@oracle.com, linux-fsdevel@vger.kernel.org, hare@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, gost.dev@samsung.com, p.raghav@samsung.com Subject: Re: [PATCH v4 05/11] mm: do not split a folio if it has minimum folio order requirement Message-ID: References: <6799F341-9E37-4F3E-B0D0-B5B2138A5F5F@nvidia.com> <202988BE-58D1-4D21-BF7F-9AECDC178D2A@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 45467180003 X-Stat-Signature: 4pkp8oh7pisxzk8sru3eqq7u3eiddmsz X-Rspam-User: X-HE-Tag: 1714573719-570894 X-HE-Meta: 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 guQsq9yE y05XgSDoI0NKJfB2YFlIdHdKV/zKk9S7pOSL9BwChxd4CJ1yJREsLwlqw1fBoqIpvScX+moZLpXq19o0t+9fL+2hjSZhP1O04/50irFB3ytyiRmTuvxVyNQGGnDaL7fzZPRspDQlkDw+GkcM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, May 01, 2024 at 05:13:59AM +0100, Matthew Wilcox wrote: > On Tue, Apr 30, 2024 at 12:27:04PM -0700, Luis Chamberlain wrote: > > 2a:* 8b 43 34 mov 0x34(%rbx),%eax <-- trapping instruction > > RBX: 0000000000000002 RCX: 0000000000018000 > > Thanks, got it. I'll send a patch in the morning, but I know exactly > what the problem is. You're seeing sibling entries tagged as dirty. > That shouldn't happen; we should only see folios tagged as dirty. > The bug is in node_set_marks() which calls node_mark_all(). This works > fine when splitting to order 0, but we should only mark the first entry > of each order. eg if we split to order 3, we should tag slots 0, 8, > 16, 24, .., 56. Confirmed: +++ b/lib/test_xarray.c @@ -1789,8 +1789,10 @@ static void check_split_1(struct xarray *xa, unsigned lon g index, { XA_STATE_ORDER(xas, xa, index, new_order); unsigned int i; + void *entry; xa_store_order(xa, index, order, xa, GFP_KERNEL); + xa_set_mark(xa, index, XA_MARK_1); xas_split_alloc(&xas, xa, order, GFP_KERNEL); xas_lock(&xas); @@ -1807,6 +1809,12 @@ static void check_split_1(struct xarray *xa, unsigned long index, xa_set_mark(xa, index, XA_MARK_0); XA_BUG_ON(xa, !xa_get_mark(xa, index, XA_MARK_0)); + xas_set_order(&xas, index, 0); + rcu_read_lock(); + xas_for_each_marked(&xas, entry, ULONG_MAX, XA_MARK_1) + XA_BUG_ON(xa, xa_is_internal(entry)); + rcu_read_unlock(); + xa_destroy(xa); } spits out: $ ./tools/testing/radix-tree/xarray BUG at check_split_1:1815 xarray: 0x562b4043e580x head 0x50c0095cc082x flags 3000000 marks 1 1 0 0-63: node 0x50c0095cc080x max 0 parent (nil)x shift 3 count 1 values 0 array 0x562b4043e580x list 0x50c0095cc098x 0x50c0095cc098x marks 1 1 0 0-7: node 0x50c0095cc140x offset 0 parent 0x50c0095cc080x shift 0 count 8 values 4 array 0x562b4043e580x list 0x50c0095cc158x 0x50c0095cc158x marks 1 ff 0 0: value 0 (0x0) [0x1x] 1: sibling (slot 0) 2: value 2 (0x2) [0x5x] 3: sibling (slot 2) 4: value 4 (0x4) [0x9x] 5: sibling (slot 4) 6: value 6 (0x6) [0xdx] 7: sibling (slot 6) xarray: ../../../lib/test_xarray.c:1815: check_split_1: Assertion `0' failed. Aborted