Messages in this thread | | | Date | Sat, 16 Apr 2011 07:43:52 +0200 | Subject | Re: [PATCH] vfs: Fix RCU path walk failiures due to uninitialized nameidata seq number for root directory | From | Sedat Dilek <> |
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On Fri, Apr 15, 2011 at 11:54 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > On Fri, Apr 15, 2011 at 2:09 PM, Andi Kleen <ak@linux.intel.com> wrote: >> On 4/15/2011 11:39 AM, Tim Chen wrote: >>> >>> During RCU walk in path_lookupat and path_openat, the rcu lookup >>> frequently failed because when root directory was looked up, seq number >>> was not properly set in nameidata. We dropped out of RCU walk in >>> nameidata_drop_rcu due to mismatch in directory entry's seq number. We >>> reverted to slow path walk that need to take references. >> >> Thanks Tim. Adding Andrew, Linus too. IMHO this fix is quite important to >> actually make the fabled RCU dcache work -- without it it's just slower >> because >> it will fallback nearly allways. > > Well, only for absolute paths, but yes. > > I think all my benchmarking was for thing like "git diff", which are > all about the relative paths and wouldn't have triggered this case. > > So this patch does look correct, and yes, should also be stable material for 38. > > And it's pretty fundamental. But I'd like to get a few more acks > exactly because it's so fundamental. Al and Nick sadly are both gone. > Anybody else feel like they know something about the path lookup code? > > Linus >
I see this patch was pushed.
What's with fs-synchronize_rcu-when-unregister_filesystem-success-not-failure.patch from [1]?
- Sedat -
[1] https://patchwork.kernel.org/patch/707322/ -- 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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