On Wednesday, 21 March 2007 22:22, Nigel Cunningham wrote: > Hi. > > On Wed, 2007-03-21 at 18:40 +0200, Maxim Levitsky wrote: > > Hi, > > > > Starting with 2.6.21-rc1 suspend to ram and disk doesn't work anymore on my > > system. > > > > I did a git-bisect and found that those commits break it: > > > > e3c7db621bed4afb8e231cb005057f2feb5db557 - [PATCH] [PATCH] PM: Change code > > ordering in main.c > > ed746e3b18f4df18afa3763155972c5835f284c5 - [PATCH] [PATCH] swsusp: Change > > code ordering in disk.c > > 259130526c267550bc365d3015917d90667732f1 - [PATCH] [PATCH] swsusp: Change > > code ordering in user.c > > > > I already reported about it, but now i know the reason why suspend breaks. > > > > The problem is that both cpu_up/cpu_down were allowed to sleep until now, > > and it did work because those functions could be called only in process > > context > > (the one that writes to /sys/devices/system/cpu/cpu*/online) or idle > > thread that does smp_init()). > > > > But now they are called _after_ all tasks were suspended, so if cpu_down > > tries for example to take a lock > > that is taken by different process, it can't since the different proccess > > is frozen and can't release the lock. > > > > I tested this and all results are positive: > > > > I disabled 2nd cpu by hand, and then suspend to ram was successfull. > > Suspend to disk went correctly, but it hang on resume, and I know why. > > It hang in old kernel trying to disable 2nd cpu that was enabled by it. > > > > I was able using kdb to confirm that this is true because it was still > > possible to enter kdb, and see that > > idle thread (swapper) was active, and uswsusp was waiting on mutex inside > > workqueue_cpu_callback. > > > > The solution for this problem seems to be ether complete audit of code that > > uses register_cpu_notifier, > > to ensure that it doesn't sleep. > > Also documentation should be changed to note about it. > > > > Or, it is also possible to revert this change. > > Do you know exactly which mutex was being waited on and where it was > taken? If you can say that, it would be much more helpful.
I think this is the XFS problem with freezable workqueues. Maxim, please try to apply the appended patch and see if it helps. Greetings, Rafael --- Since freezable workqueues are broken in 2.6.21-rc (cf. http://marc.theaimsgroup.com/?l=linux-kernel&m=116855740612755, http://marc.theaimsgroup.com/?l=linux-kernel&m=117261312523921&w=2) it's better to remove them altogether for 2.6.21 and change the only user of them (XFS) accordingly. --- fs/xfs/linux-2.6/xfs_buf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Index: linux-2.6.21-rc4/fs/xfs/linux-2.6/xfs_buf.c =================================================================== --- linux-2.6.21-rc4.orig/fs/xfs/linux-2.6/xfs_buf.c +++ linux-2.6.21-rc4/fs/xfs/linux-2.6/xfs_buf.c @@ -1829,11 +1829,11 @@ xfs_buf_init(void) if (!xfs_buf_zone) goto out_free_trace_buf; - xfslogd_workqueue = create_freezeable_workqueue("xfslogd"); + xfslogd_workqueue = create_workqueue("xfslogd"); if (!xfslogd_workqueue) goto out_free_buf_zone; - xfsdatad_workqueue = create_freezeable_workqueue("xfsdatad"); + xfsdatad_workqueue = create_workqueue("xfsdatad"); if (!xfsdatad_workqueue) goto out_destroy_xfslogd_workqueue; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
