From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Giridhar Pemmasani <pgiri@yahoo.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Allow __vmalloc with GFP_ATOMIC
Date: Sat, 28 Apr 2007 08:52:41 +0100 [thread overview]
Message-ID: <20070428075240.GA8256@flint.arm.linux.org.uk> (raw)
In-Reply-To: <539764.53941.qm@web32409.mail.mud.yahoo.com>
On Fri, Apr 27, 2007 at 09:03:33PM -0700, Giridhar Pemmasani wrote:
> Until 2.6.19, __vmalloc with GFP_ATOMIC was possible, but __get_vm_area_node
> would allocate the node itself with GFP_KERNEL, causing a warning. In 2.6.19,
> this was "fixed" by using the same flags that were passed to __vmalloc also
> in __get_vm_area_node. However, __get_vm_area_node does
> BUG_ON(in_interrupt()) now, since vmlist_lock is obtained without disabling
> bottom-half's. The patch below uses bh disabled lock for vmlist_lock, so that
> __vmalloc can be used in interrupt context.
It's worse than that. If vmalloc has to allocate a page table, the
allocation will be done as a non-atomic allocation. So, even if you
do fix __get_vm_area_node and all the other cases, if you hit a page
table allocation you'll still get a warning.
Folk need to accept that using vmalloc from atomic contexts is a
complete nono.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of:
prev parent reply other threads:[~2007-04-28 7:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-28 4:03 [PATCH] Allow __vmalloc with GFP_ATOMIC Giridhar Pemmasani
2007-04-28 4:13 ` Nick Piggin
2007-04-28 5:48 ` Giridhar Pemmasani
2007-04-28 7:52 ` Russell King [this message]
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