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rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation

From Herbert Xu <herbert@gondor.apana.org.au>
Newsgroups linux.kernel
Subject rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation
Date 2015-12-04 15:50 +0100
Message-ID <qBZQm-3Yo-27@gated-at.bofh.it> (permalink)
References (1 earlier) <qAt6b-1Ny-17@gated-at.bofh.it> <qAtIR-2gq-1@gated-at.bofh.it> <qAtIR-2gq-15@gated-at.bofh.it> <qBBEn-58q-15@gated-at.bofh.it> <qBECe-7oz-17@gated-at.bofh.it>
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On Thu, Dec 03, 2015 at 08:08:39AM -0800, Eric Dumazet wrote:
>
> Anyway, __vmalloc() can be used with GFP_ATOMIC, have you tried this ?

OK I've tried it and I no longer get any ENOMEM errors!

---8<---
When an rhashtable user pounds rhashtable hard with back-to-back
insertions we may end up growing the table in GFP_ATOMIC context.
Unfortunately when the table reaches a certain size this often
fails because we don't have enough physically contiguous pages
to hold the new table.

Eric Dumazet suggested (and in fact wrote this patch) using
__vmalloc instead which can be used in GFP_ATOMIC context.

Reported-by: Phil Sutter <phil@nwl.cc>
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index a54ff89..1c624db 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -120,8 +120,9 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 	if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER) ||
 	    gfp != GFP_KERNEL)
 		tbl = kzalloc(size, gfp | __GFP_NOWARN | __GFP_NORETRY);
-	if (tbl == NULL && gfp == GFP_KERNEL)
-		tbl = vzalloc(size);
+	if (tbl == NULL)
+		tbl = __vmalloc(size, gfp | __GFP_HIGHMEM | __GFP_ZERO,
+				PAGE_KERNEL);
 	if (tbl == NULL)
 		return NULL;
 
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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Thread

rhashtable: ENOMEM errors when hit with a flood of insertions Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-03 14:00 +0100
  RE: rhashtable: ENOMEM errors when hit with a flood of insertions David Laight <David.Laight@ACULAB.COM> - 2015-12-03 16:20 +0100
  Re: rhashtable: ENOMEM errors when hit with a flood of insertions Eric Dumazet <eric.dumazet@gmail.com> - 2015-12-03 17:10 +0100
    Re: rhashtable: ENOMEM errors when hit with a flood of insertions Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-04 01:10 +0100
    rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-04 15:50 +0100
      Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Eric Dumazet <eric.dumazet@gmail.com> - 2015-12-04 18:50 +0100
        Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Phil Sutter <phil@nwl.cc> - 2015-12-04 19:20 +0100
          Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-05 08:10 +0100
            Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Thomas Graf <tgraf@suug.ch> - 2015-12-07 16:40 +0100
              Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation David Miller <davem@davemloft.net> - 2015-12-07 20:40 +0100
                Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Thomas Graf <tgraf@suug.ch> - 2015-12-09 03:20 +0100
                Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-09 03:30 +0100
                Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-09 03:40 +0100
                Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Thomas Graf <tgraf@suug.ch> - 2015-12-09 03:50 +0100
                Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Thomas Graf <tgraf@suug.ch> - 2015-12-09 03:40 +0100
      Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation David Miller <davem@davemloft.net> - 2015-12-04 23:00 +0100
        Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation Herbert Xu <herbert@gondor.apana.org.au> - 2015-12-05 08:10 +0100
          Re: rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation David Miller <davem@davemloft.net> - 2015-12-06 04:50 +0100

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