Simon Farnsworth wrote: > Tejun Heo wrote: >> Simon Farnsworth wrote: >>> From a machine that's just done this freeze: >> [--snip--] >>> BUG: warning at kernel/softirq.c:138/local_bh_enable() (Not tainted) >>> [<c042afff>] local_bh_enable+0x45/0x96 >>> [<c0603cde>] cond_resched_softirq+0x2d/0x43 >>> [<c05d55bf>] established_get_first+0x17/0xac >>> [<c05d8f93>] tcp_seq_next+0x71/0x86 >>> [<c048c004>] seq_read+0x181/0x268 >>> [<c048be83>] seq_read+0x0/0x268 >>> [<c0476651>] vfs_read+0xab/0x15a >>> [<c0476fb7>] sys_read+0x41/0x67 >>> [<c0404ecc>] syscall_call+0x7/0xb >>> ======================= >> Hmmmm.. This is the only suspicious looking part of the kernel log and >> doesn't have too much to do with ATA freeze. 30sec - 2min delay sounds >> awfully like something caused by ATA commands timing out but libata >> always complains verbosely about those. Can you check dmesg again after >> the freeze? >> > This is a dmesg output from after the freeze. > > On machines that don't freeze, the following appears in dmesg after the > hdparm -W0 command: > > ata3.00: configured for UDMA/100 > ata3: EH complete > SCSI device sda: 156301488 512-byte hdwr sectors (80026 MB) > sda: Write Protect is off > sda: Mode Sense: 00 3a 00 00 > SCSI device sda: write cache: disabled, read cache: enabled, doesn't > support DPO or FUA > > Note that the freeze appears to be drive specific; we've seen it with > SATA Samsung drives on ata_piix, and with newer PATA Maxtor drives on > pata_via, but not with SATA Seagates on ata_piix, or with older PATA > Maxtor drives on pata_via. > > Just a thought; is it possible to trigger libata EH from userspace? If > so, we could write a small utility to disable write cache, then force EH > to detect the change. That's automatically done. libata snoops cache on/off and triggers revalidation but you can request manual rescan by echoing "- - -" to /sys/class/scsi_host/hostX/scan. -- tejun - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
