From: Christoph Hellwig <hch@lst.de> To: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Waiman Long <longman@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, linux-ext4@vger.kernel.org, cluster-devel@redhat.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 02/12] locking/rwsem: Exit early when held by an anonymous owner Date: Tue, 14 Jan 2020 17:12:15 +0100 Message-ID: <20200114161225.309792-3-hch@lst.de> (raw) In-Reply-To: <20200114161225.309792-1-hch@lst.de> The rwsem code overloads the owner field with either a task struct or negative magic numbers. Add a quick hack to catch these negative values early on. Without this spinning on a writer that replaced the owner with RWSEM_OWNER_UNKNOWN, rwsem_spin_on_owner can crash while deferencing the task_struct ->on_cpu field of a -8 value. XXX: This might be a bit of a hack as the code otherwise doesn't use the ERR_PTR family macros, better suggestions welcome. Signed-off-by: Christoph Hellwig <hch@lst.de> --- kernel/locking/rwsem.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 44e68761f432..6adc719a30a1 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -725,6 +725,8 @@ rwsem_spin_on_owner(struct rw_semaphore *sem, unsigned long nonspinnable) state = rwsem_owner_state(owner, flags, nonspinnable); if (state != OWNER_WRITER) return state; + if (IS_ERR(owner)) + return state; rcu_read_lock(); for (;;) { -- 2.24.1
next prev parent reply index Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-14 16:12 RFC: hold i_rwsem until aio completes Christoph Hellwig 2020-01-14 16:12 ` [PATCH 01/12] mm: fix a comment in sys_swapon Christoph Hellwig 2020-02-10 23:29 ` Andrew Morton 2020-02-12 7:37 ` Christoph Hellwig 2020-01-14 16:12 ` Christoph Hellwig [this message] 2020-01-14 18:17 ` [PATCH 02/12] locking/rwsem: Exit early when held by an anonymous owner Waiman Long 2020-01-14 18:25 ` Christoph Hellwig 2020-01-14 18:33 ` Waiman Long 2020-01-14 18:55 ` Waiman Long 2020-01-14 16:12 ` [PATCH 03/12] xfs: fix IOCB_NOWAIT handling in xfs_file_dio_aio_read Christoph Hellwig 2020-01-14 16:12 ` [PATCH 04/12] gfs2: move setting current->backing_dev_info Christoph Hellwig 2020-01-14 16:12 ` [PATCH 05/12] gfs2: fix O_SYNC write handling Christoph Hellwig 2020-02-06 15:31 ` [Cluster-devel] " Andreas Gruenbacher 2020-01-14 16:12 ` [PATCH 06/12] iomap: pass a flags value to iomap_dio_rw Christoph Hellwig 2020-01-14 16:12 ` [PATCH 07/12] iomap: allow holding i_rwsem until aio completion Christoph Hellwig 2020-01-14 16:12 ` [PATCH 08/12] ext4: hold i_rwsem until AIO completes Christoph Hellwig 2020-01-14 21:50 ` Theodore Y. Ts'o 2020-01-15 6:48 ` Christoph Hellwig 2020-01-14 16:12 ` [PATCH 09/12] gfs2: " Christoph Hellwig 2020-01-14 16:12 ` [PATCH 10/12] xfs: " Christoph Hellwig 2020-01-14 16:12 ` [PATCH 11/12] xfs: don't set IOMAP_DIO_SYNCHRONOUS for unaligned I/O Christoph Hellwig 2020-01-14 16:12 ` [PATCH 12/12] iomap: remove the inode_dio_begin/end calls Christoph Hellwig 2020-01-14 18:47 ` RFC: hold i_rwsem until aio completes Matthew Wilcox 2020-01-15 6:54 ` Christoph Hellwig 2020-01-14 19:27 ` Jason Gunthorpe 2020-01-15 6:56 ` Christoph Hellwig 2020-01-15 13:24 ` Jason Gunthorpe 2020-01-15 14:33 ` Peter Zijlstra 2020-01-15 14:49 ` Jason Gunthorpe 2020-01-15 19:03 ` Waiman Long 2020-01-15 19:07 ` Christoph Hellwig 2020-01-18 22:40 ` Matthew Wilcox 2020-01-15 15:36 ` Christoph Hellwig 2020-01-15 16:26 ` Jason Gunthorpe 2020-01-16 14:00 ` Jan Kara 2020-02-03 17:44 ` Christoph Hellwig 2020-01-18 9:28 ` Dave Chinner 2020-02-03 17:46 ` Christoph Hellwig 2020-02-03 23:02 ` Dave Chinner
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