[Devel] Re: [C/R] sleepers don't wake up on restart

[Oren Laadan]

Suka,

can you please post the entire test program so I can try to reproduce
it here ?

thanks,

Oren.

Sukadev Bhattiprolu wrote:
> Tried this with v14-rc2. This is probably not implemented yet...
> 
> I created a simple 1-level process tree (parent with 10 children). The 
> parent just waits for the children to exit. The children do (error
> checks removed). 
> 
> do_child():
>         sprintf(cfile, "child-log-%d", cnum);
> 
>         i = 0;
>         while (!test_done()) {
>                 cfp = fopen(cfile, "a");
>                 fprintf(cfp, "i = %d\n", i++);
>                 fflush(cfp);
>                 fclose(cfp);
>                 sleep(1);
>         }
> 
> test_done():
> 
> 	rc = access("test-done", F_OK)
> 	return rc == 0;
> 
> After freezing and restarting (using mktree), only one off 10 children makes
> progress. Others are stuck in:
> 
> 	ptree1        S f63ef170     0  8272      1
> 	 f5f17780 00000082 c2b1d5c8 f63ef170 f63ef2dc c2b20260 f5e0ff44 1c18de95
> 	 00000282 c0233594 c2b1d5c8 00000000 00000282 0000c350 00000001 0000c350
> 	 00000001 f5e0ff44 0000c350 c051b229 00000000 00000001 0000c350 bff32f44
> 	Call Trace:
> 	 [<c0233594>] hrtimer_start_range_ns+0x105/0x111
> 	 [<c051b229>] do_nanosleep+0x54/0x8c
> 	 [<c023362f>] hrtimer_nanosleep+0x8f/0xee
> 	 [<c0233210>] hrtimer_wakeup+0x0/0x18
> 	 [<c051b20f>] do_nanosleep+0x3a/0x8c
> 	 [<c02336cf>] sys_nanosleep+0x41/0x51
> 	 [<c0202ce5>] sysenter_do_call+0x12/0x25
> 
> One of them, (the 8th child) makes progress and continues to write to
> its file
> 
> 	ptree1        D f6bb7170     0  8280      1
> 	 f5de8b00 00000086 00000000 f6bb7170 f6bb72dc c2b17260 c0288ead 000165a5
> 	 c05322de c02dde8a ffffffff f6b34800 00000000 00000000 00000000 f6255d94
> 	 f5dd0700 c2b02314 f552d208 c02de045 00000000 f6e21478 00000000 f6b14600
> 	Call Trace:
> 	 [<c0288ead>] __find_get_block+0x121/0x12b
> 	 [<c02dde8a>] journal_stop+0x231/0x23d
> 	 [<c02de045>] do_get_write_access+0x1af/0x33b
> 	 [<c02310a9>] wake_bit_function+0x0/0x3c
> 	 [<c02de1e9>] journal_get_write_access+0x18/0x26
> 	 [<c02d3653>] __ext3_journal_get_write_access+0x13/0x32
> 	 [<c02c9285>] ext3_reserve_inode_write+0x2d/0x5d
> 	 [<c02c92cf>] ext3_mark_inode_dirty+0x1a/0x30
> 	 [<c02cb891>] ext3_dirty_inode+0x50/0x63
> 	 [<c0285d85>] __mark_inode_dirty+0x21/0x129
> 	 [<c027f7fa>] file_update_time+0x7e/0xa7
> 	 [<c0251c45>] __generic_file_aio_write_nolock+0x32a/0x4a1
> 	 [<c0281589>] mntput_no_expire+0x13/0xd7
> 	 [<c0251ffd>] generic_file_aio_write+0x4f/0xa6
> 	 [<c02c7bf9>] ext3_file_write+0x19/0x83
> 	 [<c0270a4d>] do_sync_write+0xbf/0x100
> 	 [<c023107c>] autoremove_wake_function+0x0/0x2d
> 	 [<c026672f>] page_add_new_anon_rmap+0x20/0x3b
> 	 [<c0260df9>] handle_mm_fault+0x1df/0x50c
> 	 [<c031d42d>] security_file_permission+0xc/0xd
> 	 [<c027098e>] do_sync_write+0x0/0x100
> 	 [<c02710dd>] vfs_write+0x83/0xf6
> 	 [<c02715a2>] sys_write+0x3c/0x63
> 
> When I create the 'test-done' file, this (8th child) exits but others are
> still sleeping (confirms they never woke up from the sleep(1))
> 
> Sukadev
> 
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