Hi, Pekka Enberg <[EMAIL PROTECTED]> wrote: > > Mathieu, Christoph is on vacation and I'm not at all that familiar > > with this cmpxchg_local() optimization, so if you could take a peek at > > this bug report to see if you can spot something obviously wrong with > > it, I would much appreciate that.
On Feb 19, 2008 12:27 PM, Ingo Molnar <[EMAIL PROTECTED]> wrote: > hm, it's bad for at least one other reason as well (which is probably > unrelated to this crash): > > /* > * Currently fastpath is not supported if preemption is enabled. > */ > #if defined(CONFIG_FAST_CMPXCHG_LOCAL) && !defined(CONFIG_PREEMPT) > #define SLUB_FASTPATH > #endif > > such !PREEMPT exceptions tend to show "i didnt want to think too hard > about the preemptible case so just turn it off" thinking. > > Also, why isnt this "SLUB_FASTPATH" flag done in the Kconfig space? Hmm, no idea. I think might have been some mix-up with merging the patch. The one I saw was: http://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.24/2.6.24-mm1/broken-out/slub-optional-fast-path-using-cmpxchg_local.patch But I don't remember giving out a Reviewed-by for it (and my mailbox confirms that). Furthermore, somehow it turned into this when merged: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=1f84260c8ce3b1ce26d4c1d6dedc2f33a3a29c0c In any case, if Torsten/someone can verify that reverting 1f84260c8ce3b1ce26d4c1d6dedc2f33a3a29c0c ("SLUB: Alternate fast paths using cmpxchg_local") fixes these problems, I think we should just do it and let Christoph sort it out when he gets back. Pekka -- 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/
