On Sun, Jul 09, 2017 at 05:01:25PM +0000, Markus Stockhausen wrote: > > -----Ursprüngliche Nachricht----- > > Von: Darrick J. Wong [mailto:darrick.wong@xxxxxxxxxx] > > Gesendet: Freitag, 7. Juli 2017 05:47 > > An: Markus Stockhausen > > Cc: 'linux-xfs@xxxxxxxxxxxxxxx' > > Betreff: Re: XFS hang - 4.4.73 longterm > > > > > > ... > > > > This is the known deadlock in SEEK_HOLE/SEEK_DATA; I have patches queued to fix it in 4.13, as soon as the dust settles and I send the pull req. > > > > > > Short, precise, frightening. > > > > > > Can you advise what will the best option to avoid that error. > > > First things that come to my mind would be: > > > > > > - get back to original 3.10 stable kernel from CentOS Distro > > > - lower NFS mount version > > > - Maybe remove some single patch that introduced the error? > > > > Unfortunately, SEEK_HOLE (and the deadlocky code) go all the way back to the beginning of SEEK_HOLE support, so I don't know that > > there's a good workaround for this. There's not really a way to shut off support for it, either, that doesn't involve gross code surgery. > > Not good news. Finally I disabled SEEK support in nfsd by partially > reverting 3.18 patch 24bab491220faa446d94 "NFSD: Implement SEEK". > While before NFS/XFS crashed with active VM snapshots and heavy disk > writes after minutes it now runs for 2 days of intensive testing > without errors. > > At least now I have full discard support in side VMs (via hole > punching of disk files). I'd advise you to set an extent size hint to reduce fragmentation, the same as we tell everyone else. :) I'd also advise you not to punch too many holes in the VM files because that increases extent map overhead. There's also an unfortunate design problem in the in-memory extent map -- all the extents have to fit in a single chunk of memory -- and punching a lot of small holes when memory is tight can lead to allocation failures. (Even after we fix that problem I'd still advise against punching a lot of small holes purely due to the overhead that creates.) > I'm not familiar with SEEK_HOLE/SEEK_data feature. Do you see negative > impact if disabling these? In contrast to falling back to NFS 4 > without seek + discard support. Well, whatever program was using SEEK_{HOLE,DATA} to skip sparse holes in the files will likely revert to a much slower "read the whole file looking for block aligned zeroes" algorithm... assuming that was why it was doing that in the first place. FWIW I just sent off the 4.13 merge request with the SEEK_HOLE fixes, though they depend on iomap, which (iirc) wasn't added to the vfs until 4.8 or so. --D > > Markus > **************************************************************************** > Diese E-Mail enth??lt vertrauliche und/oder rechtlich gesch??tzte > Informationen. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail > irrt??mlich erhalten haben, informieren Sie bitte sofort den Absender und > vernichten Sie diese Mail. Das unerlaubte Kopieren sowie die unbefugte > Weitergabe dieser Mail ist nicht gestattet. > > ??ber das Internet versandte E-Mails k??nnen unter fremden Namen erstellt oder > manipuliert werden. Deshalb ist diese als E-Mail verschickte Nachricht keine > rechtsverbindliche Willenserkl??rung. > > Collogia > Unternehmensberatung AG > Ubierring 11 > D-50678 K??ln > > Vorstand: > Kadir Akin > Dr. Michael H??hnerbach > > Vorsitzender des Aufsichtsrates: > Hans Kristian Langva > > Registergericht: Amtsgericht K??ln > Registernummer: HRB 52 497 > > This e-mail may contain confidential and/or privileged information. If you > are not the intended recipient (or have received this e-mail in error) > please notify the sender immediately and destroy this e-mail. Any > unauthorized copying, disclosure or distribution of the material in this > e-mail is strictly forbidden. > > e-mails sent over the internet may have been written under a wrong name or > been manipulated. That is why this message sent as an e-mail is not a > legally binding declaration of intention. > > Collogia > Unternehmensberatung AG > Ubierring 11 > D-50678 K??ln > > executive board: > Kadir Akin > Dr. Michael H??hnerbach > > President of the supervisory board: > Hans Kristian Langva > > Registry office: district court Cologne > Register number: HRB 52 497 > > **************************************************************************** -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
