From: Dmitry Safonov <dima@arista.com>
To: Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Dmitry Safonov <0x7f454c46@gmail.com>,
linux-kernel@vger.kernel.org
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
David Ahern <dsahern@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Ido Schimmel <idosch@mellanox.com>,
netdev@vger.kernel.org
Subject: Re: [RFC 1/4] net/ipv4/fib: Remove run-time check in tnode_alloc()
Date: Thu, 4 Apr 2019 17:33:54 +0100 [thread overview]
Message-ID: <992772b9-3565-c616-614b-303fcc078978@arista.com> (raw)
In-Reply-To: <b3540257a002b944a878096570bc927450662b9c.camel@linux.intel.com>
On 4/1/19 6:50 PM, Alexander Duyck wrote:
> On Mon, 2019-04-01 at 16:55 +0100, Dmitry Safonov wrote:
> Actually now that I think about it TNODE_VMALLOC_MAX is likely much
> less than 31. The logic that we have to be concerned with is:
> size = TNODE_SIZE(1ul << bits);
>
> If size is a 32b value, and the size of a pointer is 4 bytes, then our
> upper limit is roughly ilog2((4G - 28) / 4), which comes out to 29.
> What we are trying to avoid is overflowing the size variable, not
> actually limiting the vmalloc itself.
Oh yes, I see - managed to forget that size can also overflow inside
TNODE_SIZE().
>> So, I wanted to remove run-time check here on x86_64..
>> I could do it by adding !CONFIG_64BIT around the check.
>
> I have no problem with that. All I am suggesting is that if at all
> possible we should use TNODE_VMALLOC_MAX instead of BITS_PER_LONG.
Yeah, will rework this part.
Thanks,
Dmitry
next prev parent reply other threads:[~2019-04-04 16:34 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 15:30 [RFC 0/4] net/fib: Speed up trie rebalancing for full view Dmitry Safonov
2019-03-26 15:30 ` [RFC 1/4] net/ipv4/fib: Remove run-time check in tnode_alloc() Dmitry Safonov
2019-04-01 15:40 ` Alexander Duyck
2019-04-01 15:55 ` Dmitry Safonov
2019-04-01 17:50 ` Alexander Duyck
2019-04-04 16:33 ` Dmitry Safonov [this message]
2019-03-26 15:30 ` [RFC 2/4] net/fib: Provide fib_balance_budget sysctl Dmitry Safonov
2019-04-01 18:09 ` Alexander Duyck
2019-04-04 18:31 ` Dmitry Safonov
2019-03-26 15:30 ` [RFC 3/4] net/fib: Check budget before should_{inflate,halve}() Dmitry Safonov
2019-04-01 18:20 ` Alexander Duyck
2019-03-26 15:30 ` [RFC 4/4] net/ipv4/fib: Don't synchronise_rcu() every 512Kb Dmitry Safonov
2019-03-26 15:39 ` David Ahern
2019-03-26 17:15 ` Dmitry Safonov
2019-03-26 17:57 ` David Ahern
2019-03-26 18:17 ` Dmitry Safonov
2019-03-26 23:14 ` Dmitry Safonov
2019-03-27 3:33 ` Paul E. McKenney
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