Hi, I encountered the following problem. We use short expiration time for kerberos contexts created by rpc.gssd (some patches were included in mainline nfs-utils). In particular, we use 120secs expiration time. Now, I run application that eats 80% of available RAM. Then I run 10 parallel dd processes that write data into NFS4 volume with sec=krb5. As soon as the kerberos context expires (i.e., up to 120 secs), the whole system gets stuck in do_page_fault and succesive functions. It is because there is no free memory in kernel, all free memory is used as cache for NFS4 (due to dd traffic), kernel ask NFS to write back its pages but NFS cannot do anything as it is missing valid context. NFS contacts rpc.gssd to provide a renewed context, the rpc.gssd does not provide the context as it needs some memory to scan /tmp for a ticket. I.e., it deadlocks. Longer context expiration time is no real solution as it only makes the deadlock less often. Any ideas what can be done here? (Please cc me.) We could preallocate some memory in rpc.gssd and use mlockall but not sure whether this proctects also kernel malloc for things related to rpc.gssd and context creation (new file descriptors and so on). This is seen in 2.6.32 kernel but most probably this is related to all kernel versions. rpc.gssd and all dd processes are stuck in: May 6 15:33:10 skirit20 kernel: [84087.788019] rpc.gssd D 6758d881 0 26864 1 0x00000000 May 6 15:33:10 skirit20 kernel: [84087.788019] c280594c 00000086 f94c3d6c 6758d881 00004c5a 0f3e1c27 c1d868c0 c1c068dc May 6 15:33:10 skirit20 kernel: [84087.788019] c07d8880 c07d8880 f6752130 f67523d4 c1c06880 00000000 c1c06880 00000000 May 6 15:33:10 skirit20 kernel: [84087.788019] f6d7c8f0 f67523d4 f6752130 c1c06cd4 c1c06880 c2805960 c052101f 00000000 May 6 15:33:10 skirit20 kernel: [84087.788019] Call Trace: May 6 15:33:10 skirit20 kernel: [84087.788019] [<c052101f>] io_schedule+0x6f/0xc0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<f88d8af5>] nfs_wait_bit_uninterruptible+0x5/0x10 [nfs] May 6 15:33:10 skirit20 kernel: [84087.788019] [<c05215a7>] __wait_on_bit+0x47/0x70 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c0521683>] out_of_line_wait_on_bit+0xb3/0xd0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<f88d8ae3>] nfs_wait_on_request+0x23/0x30 [nfs] May 6 15:33:10 skirit20 kernel: [84087.788019] [<f88ddb4a>] nfs_sync_mapping_wait+0xea/0x200 [nfs] May 6 15:33:10 skirit20 kernel: [84087.788019] [<f88ddd0e>] nfs_wb_page_priority+0xae/0x170 [nfs] May 6 15:33:10 skirit20 kernel: [84087.788019] [<f88cdfec>] nfs_release_page+0x5c/0x70 [nfs] May 6 15:33:10 skirit20 kernel: [84087.788019] [<c029620b>] try_to_release_page+0x2b/0x40 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02a25af>] shrink_page_list+0x37f/0x4b0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02a29ae>] shrink_inactive_list+0x2ce/0x6c0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02a34c8>] shrink_zone+0x1c8/0x260 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02a35ae>] shrink_zones+0x4e/0xe0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02a43b5>] do_try_to_free_pages+0x75/0x2e0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02a4756>] try_to_free_pages+0x86/0xa0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c029cda4>] __alloc_pages_slowpath+0x164/0x470 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c029d1c8>] __alloc_pages_nodemask+0x118/0x120 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02acce0>] do_anonymous_page+0x100/0x240 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02b072a>] handle_mm_fault+0x34a/0x3d0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c0524c54>] do_page_fault+0x174/0x370 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c0522cb6>] error_code+0x66/0x70 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c0296ac2>] file_read_actor+0x32/0xf0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c029815f>] do_generic_file_read+0x3af/0x4c0 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c0298a01>] generic_file_aio_read+0xb1/0x210 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02cdc05>] do_sync_read+0xd5/0x120 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02ce3bb>] vfs_read+0x9b/0x110 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c02ce501>] sys_read+0x41/0x80 May 6 15:33:10 skirit20 kernel: [84087.788019] [<c0203150>] sysenter_do_call+0x12/0x22 May 6 15:33:10 skirit20 kernel: [84087.788019] [<ffffe430>] 0xffffe430 -- Lukáš Hejtmánek -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
