Messages in this thread | | | Subject | Re: [PATCH v6 16/24] mm: Protect mm_rb tree with a rwlock | From | Laurent Dufour <> | Date | Mon, 15 Jan 2018 18:42:11 +0100 |
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Hi Matthew,
Thanks for reviewing this series.
On 12/01/2018 19:48, Matthew Wilcox wrote: > On Fri, Jan 12, 2018 at 06:26:00PM +0100, Laurent Dufour wrote: >> -static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) >> +static void __vma_rb_erase(struct vm_area_struct *vma, struct mm_struct *mm) >> { >> + struct rb_root *root = &mm->mm_rb; >> /* >> * Note rb_erase_augmented is a fairly large inline function, >> * so make sure we instantiate it only once with our desired >> * augmented rbtree callbacks. >> */ >> +#ifdef CONFIG_SPF >> + write_lock(&mm->mm_rb_lock); >> +#endif >> rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); >> +#ifdef CONFIG_SPF >> + write_unlock(&mm->mm_rb_lock); /* wmb */ >> +#endif > > I can't say I love this. Have you considered: > > #ifdef CONFIG_SPF > #define vma_rb_write_lock(mm) write_lock(&mm->mm_rb_lock) > #define vma_rb_write_unlock(mm) write_unlock(&mm->mm_rb_lock) > #else > #define vma_rb_write_lock(mm) do { } while (0) > #define vma_rb_write_unlock(mm) do { } while (0) > #endif
I haven't consider this, but this sounds to be smarter. I'll do that.
> Also, SPF is kind of uninformative. CONFIG_MM_SPF might be better? > Or perhaps even CONFIG_SPECULATIVE_PAGE_FAULT, just to make it really > painful to do these one-liner ifdefs that make the code so hard to read.
Thomas also complained about that, and I agree, SPF is quite cryptic. This being said, I don't think that CONFIG_MM_SPF will be far better, so I'll change this define to CONFIG_SPECULATIVE_PAGE_FAULT, even if it's longer, it should not be too much present in the code.
Thanks, Laurent.
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