From: Blaisorblade <blaisorblade@yahoo.it>
To: user-mode-linux-devel@lists.sourceforge.net,
Jeff Dike <jdike@addtoit.com>,
Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Subject: [uml-devel] Sleeping function in atomic - 2.6.11
Date: Fri, 11 Mar 2005 19:35:40 +0100 [thread overview]
Message-ID: <200503111935.40714.blaisorblade@yahoo.it> (raw)
This happened with CONFIG_HIGHMEM enabled on a almost-vanilla 2.6.11... with
that option disabled I don't see such problems (also tested on both the same
exact kernel, and with nearby ones).
To sum up, there is a read() syscall, a copy_to_user() (which calls kmap())
with preemption disabled (in_atomic() == 1) and the might_sleep produces a
warning... now, what's strange is that UML is always built with preemption
disabled (will this mean in_atomic == 1 always?).
And also I don't understand what changes with HIGHMEM... it seems that kmap
always calls might_sleep().
Debug: sleeping function called from invalid context at
arch/um/sys-i386/highmem.c:5
in_atomic():1, irqs_disabled():0
Call Trace:
0bdd77a0: [<08079cec>] __might_sleep+0xac/0xd0
0bdd77c0: [<0807676d>] kmap+0x1d/0x40
0bdd77d0: [<08061417>] do_op+0x37/0x70
0bdd77f0: [<080614ca>] do_buffer_op+0x7a/0x1a0
0bdd7800: [<08061780>] copy_chunk_to_user+0x0/0x40
0bdd7810: [<08061780>] copy_chunk_to_user+0x0/0x40
0bdd7830: [<0805f7e1>] setjmp_wrapper+0x51/0x60
0bdd783c: [<08237b45>] sigemptyset+0x25/0x40
0bdd7868: [<0805f7ac>] setjmp_wrapper+0x1c/0x60
0bdd78ac: [<08237b45>] sigemptyset+0x25/0x40
0bdd78c0: [<0805c17b>] change_signals+0x5b/0x90
0bdd7900: [<08061631>] buffer_op+0x41/0x80
0bdd7904: [<08061450>] do_buffer_op+0x0/0x1a0
0bdd7914: [<08061780>] copy_chunk_to_user+0x0/0x40
0bdd7930: [<0806183e>] copy_to_user_skas+0x7e/0xc0
0bdd7940: [<08061780>] copy_chunk_to_user+0x0/0x40
0bdd7960: [<080b053f>] file_read_actor+0xcf/0x150
0bdd7990: [<080b02a7>] do_generic_mapping_read+0x607/0x7d0
0bdd79b0: [<0805c219>] enable_mask+0x49/0x60
0bdd7a40: [<080b0770>] __generic_file_aio_read+0x1b0/0x220
0bdd7a58: [<080b0470>] file_read_actor+0x0/0x150
0bdd7a88: [<080ba2ae>] poison_obj+0x2e/0x60
0bdd7aa0: [<080b0953>] generic_file_read+0xd3/0x100
0bdd7b20: [<080a2fe0>] autoremove_wake_function+0x0/0x60
0bdd7b50: [<080e0534>] vfs_read+0xe4/0x180
0bdd7b80: [<080e0901>] sys_read+0x51/0x80
0bdd7bb0: [<08060c87>] execute_syscall_skas+0xd7/0x100
0bdd7bd0: [<08280e04>] schedule+0x3a4/0x6f0
0bdd7c20: [<0805cb79>] record_syscall_start+0x59/0x70
0bdd7c40: [<08060ce9>] handle_syscall+0x39/0x70
0bdd7c60: [<080600d1>] userspace+0x231/0x3b0
0bdd7c90: [<080779d9>] finish_task_switch+0x79/0x110
0bdd7cd0: [<080611e8>] force_flush_all_skas+0x38/0x40
0bdd7cf0: [<080608dc>] fork_handler+0xbc/0xd0
0bdd7d20: [<08237738>] __restore+0x0/0x8
0bdd7d60: [<08237ab1>] kill+0x11/0x20
--
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade
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