Messages in this thread | | | From | Linus Torvalds <> | Date | Thu, 24 May 2018 10:53:26 -0700 | Subject | Re: semantics of rhashtable and sysvipc |
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On Thu, May 24, 2018 at 10:23 AM Davidlohr Bueso <dave@stgolabs.net> wrote:
> tbl = bucket_table_alloc(ht, size, GFP_KERNEL); > - if (tbl == NULL) > - return -ENOMEM; > + if (unlikely(tbl == NULL)) { > + size = min(size, HASH_DEFAULT_SIZE) / 2; > + > + tbl = bucket_table_alloc(ht, size, GFP_KERNEL); > + if (tbl == NULL) > + tbl = bucket_table_alloc_retry(ht, size, GFP_KERNEL); > + }
This doesn't seem to be taking 'param->min_size' into account.
I'm not sure that matters, but right now, if you have nelem_hint set and a min_size, the min_size is honored (if you have just min_size it's already ignored because the rhashtable always starts with HASH_DEFAULT_SIZE). So I could imagine that somebody uses it to guarantee something. The docs say that "min_size" is the minimum size for *shrinking* not for initializing, so I guess it's debatable.
Also, wouldn't it make sense to make this all be a while loop? Or are you just depending on the knowledge that HASH_DEFAULT_SIZE / 2 is already guaranteed to be so small that there's no point? A comment to that effect would be good, perhaps.
Linus
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