From: "H. Peter Anvin" <hpa@zytor.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [RFC PATCH] Fix: x86 unaligned __memcpy to/from virtual memory
Date: Wed, 24 Jun 2015 11:53:23 -0700 [thread overview]
Message-ID: <558AFCA3.9010401@zytor.com> (raw)
In-Reply-To: <609198255.2568.1435171747039.JavaMail.zimbra@efficios.com>
On 06/24/2015 11:49 AM, Mathieu Desnoyers wrote:
>
> [ 53.084521] DEBUG: vmalloc_fault at address 0xffffc9000746e000
> [ 53.085460] BUG: unable to handle kernel paging request at ffffc9000746e000
> [ 53.085460] IP:
> [ 53.090220] [<ffffffff81316f12>] __memcpy+0x12/0x20
> [ 53.090220] PGD 236c92067 PUD 236c93067 PMD 22e840067 PTE 0
> [ 53.090220] Oops: 0000 [#1] SMP
> [ 53.090220] Modules linked in: lttng_probe_workqueue(O) lttng_probe_vmscan(O) lttng_probe_udp(O) lttng_probe_timer(O) lttng_probe_sunrpc(O) lttng_probe_statedump(O) lttng_probe_sock(O) lttng_probe_skb(O) lttng_probe_signal(O) lttng_probe_scsi(O) lttng_probe_sched(O) lttng_probe_regmap(O) lttng_probe_rcu(O) lttng_probe_random(O) lttng_probe_power(O) lttng_probe_net(O) lttng_probe_napi(O) lttng_probe_module(O) lttng_probe_kmem(O) lttng_probe_jbd2(O) lttng_probe_irq(O) lttng_probe_ext4(O) lttng_probe_compaction(O) lttng_probe_block(O) lttng_types(O) lttng_ring_buffer_metadata_mmap_client(O) lttng_ring_buffer_client_mmap_overwrite(O) lttng_ring_buffer_client_mmap_discard(O) lttng_ring_buffer_metadata_client(O) lttng_ring_buffer_client_overwrite(O) lttng_ring_buffer_client_discard(O) lttng_tracer(O) lttng_statedump(O) lttng_kprobes(O) lttng_lib_ring_buffer(O) lttng_kretprobes(O) virtio_blk virtio_net virtio_pci virtio_ring virtio [last unloaded: lttng_statedump]
> [ 53.090220] CPU: 4 PID: 3532 Comm: lttng-consumerd Tainted: G O 4.1.0+ #10
> [ 53.090220] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> [ 53.090220] task: ffff880235355aa0 ti: ffff8800bb6d0000 task.ti: ffff8800bb6d0000
> [ 53.090220] RIP: 0010:[<ffffffff81316f12>] [<ffffffff81316f12>] __memcpy+0x12/0x20
> [ 53.090220] RSP: 0018:ffff8800bb6d3da0 EFLAGS: 00010206
> [ 53.090220] RAX: ffff8802355b3025 RBX: 0000000000000fdb RCX: 00000000000001fb
> [ 53.090220] RDX: 0000000000000003 RSI: ffffc9000746e000 RDI: ffff8802355b3025
Okay, RSI is at the start of a page, but isn't even unaligned. RDI is
unaligned, but that shouldn't matter at all.
So I think the problem is really that you are simply outrunning your
input buffer.
-hpa
next prev parent reply other threads:[~2015-06-24 18:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-24 16:14 [RFC PATCH] Fix: x86 unaligned __memcpy to/from virtual memory Mathieu Desnoyers
2015-06-24 17:00 ` Linus Torvalds
2015-06-24 18:49 ` Mathieu Desnoyers
2015-06-24 18:53 ` H. Peter Anvin [this message]
2015-06-24 19:15 ` Linus Torvalds
2015-06-24 23:54 ` Mathieu Desnoyers
2015-06-25 0:33 ` Mathieu Desnoyers
2015-06-25 0:37 ` Linus Torvalds
2015-06-25 12:58 ` Mathieu Desnoyers
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