Messages in this thread | | | Date | Wed, 18 Jun 2014 16:31:11 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH 2/2] fs/seq_file: fallback to vmalloc allocation |
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On Mon, 16 Jun 2014, Heiko Carstens wrote:
> There are a couple of seq_files which use the single_open() interface. > This interface requires that the whole output must fit into a single buffer. > > E.g. for /proc/stat allocation failures have been observed because an order-4 > memory allocation failed due to memory fragmentation. In such situations > reading /proc/stat is not possible anymore. > > Therefore change the seq_file code to fallback to vmalloc allocations which > will usually result in a couple of order-0 allocations and hence also work > if memory is fragmented. > > For reference a call trace where reading from /proc/stat failed: > > [62129.701569] sadc: page allocation failure: order:4, mode:0x1040d0 > [62129.701573] CPU: 1 PID: 192063 Comm: sadc Not tainted 3.10.0-123.el7.s390x #1 > [...] > [62129.701586] Call Trace: > [62129.701588] ([<0000000000111fbe>] show_trace+0xe6/0x130) > [62129.701591] [<0000000000112074>] show_stack+0x6c/0xe8 > [62129.701593] [<000000000020d356>] warn_alloc_failed+0xd6/0x138 > [62129.701596] [<00000000002114d2>] __alloc_pages_nodemask+0x9da/0xb68 > [62129.701598] [<000000000021168e>] __get_free_pages+0x2e/0x58 > [62129.701599] [<000000000025a05c>] kmalloc_order_trace+0x44/0xc0 > [62129.701602] [<00000000002f3ffa>] stat_open+0x5a/0xd8 > [62129.701604] [<00000000002e9aaa>] proc_reg_open+0x8a/0x140 > [62129.701606] [<0000000000273b64>] do_dentry_open+0x1bc/0x2c8 > [62129.701608] [<000000000027411e>] finish_open+0x46/0x60 > [62129.701610] [<000000000028675a>] do_last+0x382/0x10d0 > [62129.701612] [<0000000000287570>] path_openat+0xc8/0x4f8 > [62129.701614] [<0000000000288bde>] do_filp_open+0x46/0xa8 > [62129.701616] [<000000000027541c>] do_sys_open+0x114/0x1f0 > [62129.701618] [<00000000005b1c1c>] sysc_tracego+0x14/0x1a > > Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: David Rientjes <rientjes@google.com>
Very nice!
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