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Groups > linux.kernel > #1186359
| From | Dave Chinner <david@fromorbit.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH RFC 0/4] change sb_writers to use percpu_rw_semaphore |
| Date | 2015-07-17 03:30 +0200 |
| Message-ID | <pN2Do-7lA-7@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <pMgfo-4h4-25@gated-at.bofh.it> <pMoFX-83L-19@gated-at.bofh.it> <pMzBp-7sZ-33@gated-at.bofh.it> <pMLMe-8fr-11@gated-at.bofh.it> <pMViz-57c-43@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Jul 16, 2015 at 07:32:56PM +0200, Oleg Nesterov wrote: > > #ifdef CONFIG_LOCKDEP > /* > * We want lockdep to tell us about possible deadlocks with freezing but > * it's it bit tricky to properly instrument it. Getting a freeze protection > * works as getting a read lock but there are subtle problems. XFS for example > * gets freeze protection on internal level twice in some cases, which is OK Sorry, I've missed something here - where is XFS nesting sb_start_intwrite() calls? XFS only has a call to sb_start_intwrite() in xfs_trans_alloc() and an open coded equivalent in xfs_iomap_write_unwritten(). However, we cannot create nested transaction contexts as doing so is *guaranteed to deadlock the journal*. (e.g. why we use PF_FSTRANS to trigger GFP_NOFS allocation as it prevents direct memory reclaim from causing nested transactions.) Hence if we taking multiple FREEZE_FS level references at a time then there is a bug that needs fixing.... Cheers, Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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Re: [PATCH RFC 0/4] change sb_writers to use percpu_rw_semaphore Jan Kara <jack@suse.cz> - 2015-07-15 08:50 +0200
Re: [PATCH RFC 0/4] change sb_writers to use percpu_rw_semaphore Jan Kara <jack@suse.cz> - 2015-07-16 12:20 +0200
Re: [PATCH RFC 0/4] change sb_writers to use percpu_rw_semaphore Oleg Nesterov <oleg@redhat.com> - 2015-07-16 19:40 +0200
Re: [PATCH RFC 0/4] change sb_writers to use percpu_rw_semaphore Dave Chinner <david@fromorbit.com> - 2015-07-17 03:30 +0200
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