Hi, My test board (ARM, Exynos5422, Odroid XU3) booted from NFS root (NFS v4) hit a sleep in a atomic context: BUG: sleeping function called from invalid context at ../mm/slab.h:395 in_atomic(): 1, irqs_disabled(): 0, pid: 232, name: kworker/u16:0 2 locks held by kworker/u16:0/232: #0: (&sig->cred_guard_mutex){......}, at: [<c042e410>] prepare_bprm_creds+0x28/0x74 #1: (rcu_read_lock){......}, at: [<c04f304c>] nfs_permission+0x68/0x23c CPU: 3 PID: 232 Comm: kworker/u16:0 Not tainted 4.7.0-rc3-next-20160615 #633 Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [<c0310dd8>] (unwind_backtrace) from [<c030c448>] (show_stack+0x10/0x14) [<c030c448>] (show_stack) from [<c05b6f8c>] (dump_stack+0x90/0xa4) [<c05b6f8c>] (dump_stack) from [<c041f77c>] (kmem_cache_alloc+0xe8/0x170) [<c041f77c>] (kmem_cache_alloc) from [<c04f4ac8>] (nfs_alloc_fattr+0x1c/0x30) [<c04f4ac8>] (nfs_alloc_fattr) from [<c04f6d38>] (__nfs_revalidate_inode+0x30/0x140) [<c04f6d38>] (__nfs_revalidate_inode) from [<c04f2f20>] (nfs_do_access+0x220/0x2b8) [<c04f2f20>] (nfs_do_access) from [<c04f30a8>] (nfs_permission+0xc4/0x23c) [<c04f30a8>] (nfs_permission) from [<c042d7a0>] (would_dump+0x18/0x2c) [<c042d7a0>] (would_dump) from [<c0474eec>] (load_elf_binary+0x5a8/0x1258) [<c0474eec>] (load_elf_binary) from [<c042d8dc>] (search_binary_handler+0x84/0x1c0) [<c042d8dc>] (search_binary_handler) from [<c042e948>] (do_execveat_common+0x4ec/0x6c8) [<c042e948>] (do_execveat_common) from [<c042eb48>] (do_execve+0x24/0x2c) [<c042eb48>] (do_execve) from [<c035741c>] (call_usermodehelper_exec_async+0x128/0x180) [<c035741c>] (call_usermodehelper_exec_async) from [<c0308078>] (ret_from_fork+0x14/0x3c) BUG: scheduling while atomic: kworker/u16:0/232/0x00000002 2 locks held by kworker/u16:0/232: #0: (&sig->cred_guard_mutex){......}, at: [<c042e410>] prepare_bprm_creds+0x28/0x74 #1: (rcu_read_lock){......}, at: [<c04f304c>] nfs_permission+0x68/0x23c Modules linked in: ohci_exynos phy_exynos_usb2 CPU: 3 PID: 232 Comm: kworker/u16:0 Not tainted 4.7.0-rc3-next-20160615 #633 Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [<c0310dd8>] (unwind_backtrace) from [<c030c448>] (show_stack+0x10/0x14) [<c030c448>] (show_stack) from [<c05b6f8c>] (dump_stack+0x90/0xa4) [<c05b6f8c>] (dump_stack) from [<c0364cfc>] (__schedule_bug+0x58/0x6c) [<c0364cfc>] (__schedule_bug) from [<c0bcfd00>] (__schedule+0x49c/0x600) [<c0bcfd00>] (__schedule) from [<c0bcfeb4>] (schedule+0x50/0xb4) [<c0bcfeb4>] (schedule) from [<c0bac058>] (rpc_wait_bit_killable+0x28/0xfc) [<c0bac058>] (rpc_wait_bit_killable) from [<c0bd03c0>] (__wait_on_bit+0x84/0xb8) [<c0bd03c0>] (__wait_on_bit) from [<c0bd04b8>] (out_of_line_wait_on_bit+0xc4/0xcc) [<c0bd04b8>] (out_of_line_wait_on_bit) from [<c0baca94>] (__rpc_execute+0x194/0x26c) [<c0baca94>] (__rpc_execute) from [<c0ba67b4>] (rpc_run_task+0x134/0x14c) [<c0ba67b4>] (rpc_run_task) from [<c0509010>] (nfs4_call_sync_sequence+0x58/0x78) [<c0509010>] (nfs4_call_sync_sequence) from [<c050efcc>] (nfs4_proc_getattr+0xb8/0xe0) [<c050efcc>] (nfs4_proc_getattr) from [<c04f6d94>] (__nfs_revalidate_inode+0x8c/0x140) [<c04f6d94>] (__nfs_revalidate_inode) from [<c04f2f20>] (nfs_do_access+0x220/0x2b8) [<c04f2f20>] (nfs_do_access) from [<c04f30a8>] (nfs_permission+0xc4/0x23c) [<c04f30a8>] (nfs_permission) from [<c042d7a0>] (would_dump+0x18/0x2c) [<c042d7a0>] (would_dump) from [<c0474eec>] (load_elf_binary+0x5a8/0x1258) [<c0474eec>] (load_elf_binary) from [<c042d8dc>] (search_binary_handler+0x84/0x1c0) [<c042d8dc>] (search_binary_handler) from [<c042e948>] (do_execveat_common+0x4ec/0x6c8) [<c042e948>] (do_execveat_common) from [<c042eb48>] (do_execve+0x24/0x2c) [<c042eb48>] (do_execve) from [<c035741c>] (call_usermodehelper_exec_async+0x128/0x180) [<c035741c>] (call_usermodehelper_exec_async) from [<c0308078>] (ret_from_fork+0x14/0x3c) Full log here: http://www.krzk.eu/builders/boot-odroid-xu3-multi_v7/builds/1166/steps/Boot%3A%20odroidxu3/logs/serial0 Config: arm/multi_v7_defconfig with following changes: -e IPV6 -e NFS_V4 -e SENSORS_PWM_FAN -e PWM_SAMSUNG -d CRYPTO_MANAGER_DISABLE_TESTS -e DMATEST -m CRYPTO_TEST -e SCHED_STACK_END_CHECK -e DEBUG_LOCK_ALLOC -e DEBUG_ATOMIC_SLEEP -e DEBUG_LIST -e DEBUG_SECTION_MISMATCH I hope that information might be useful. Please let me know if you need more details (I didn't bisect this...). Best regards, Krzysztof -- 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