From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx113.postini.com [74.125.245.113]) by kanga.kvack.org (Postfix) with SMTP id D0DCB6B0034 for ; Tue, 23 Jul 2013 18:12:58 -0400 (EDT) Message-ID: <51EEFFAD.701@infradead.org> Date: Tue, 23 Jul 2013 15:11:57 -0700 From: Randy Dunlap MIME-Version: 1.0 Subject: Re: [PATCH v2] lib: Make radix_tree_node_alloc() work correctly within interrupt References: <1374617060-25805-1-git-send-email-jack@suse.cz> In-Reply-To: <1374617060-25805-1-git-send-email-jack@suse.cz> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: Andrew Morton , LKML , linux-mm@kvack.org, Jens Axboe On 07/23/13 15:04, Jan Kara wrote: Hi, s/sence/sense/ please. > > diff --git a/lib/radix-tree.c b/lib/radix-tree.c > index e796429..7811ed3 100644 > --- a/lib/radix-tree.c > +++ b/lib/radix-tree.c > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include /* in_interrupt() */ > > > #ifdef __KERNEL__ > @@ -207,7 +208,12 @@ radix_tree_node_alloc(struct radix_tree_root *root) > struct radix_tree_node *ret = NULL; > gfp_t gfp_mask = root_gfp_mask(root); > > - if (!(gfp_mask & __GFP_WAIT)) { > + /* > + * Preload code isn't irq safe and it doesn't make sence to use sense > + * preloading in the interrupt anyway as all the allocations have to > + * be atomic. So just do normal allocation when in interrupt. > + */ > + if (!(gfp_mask & __GFP_WAIT) && !in_interrupt()) { > struct radix_tree_preload *rtp; > > /* > @@ -264,7 +270,7 @@ radix_tree_node_free(struct radix_tree_node *node) > * To make use of this facility, the radix tree must be initialised without > * __GFP_WAIT being passed to INIT_RADIX_TREE(). > */ > -int radix_tree_preload(gfp_t gfp_mask) > +static int __radix_tree_preload(gfp_t gfp_mask) > { > struct radix_tree_preload *rtp; > struct radix_tree_node *node; > @@ -288,9 +294,40 @@ int radix_tree_preload(gfp_t gfp_mask) > out: > return ret; > } > + > +/* > + * Load up this CPU's radix_tree_node buffer with sufficient objects to > + * ensure that the addition of a single element in the tree cannot fail. On > + * success, return zero, with preemption disabled. On error, return -ENOMEM > + * with preemption not disabled. > + * > + * To make use of this facility, the radix tree must be initialised without > + * __GFP_WAIT being passed to INIT_RADIX_TREE(). > + */ > +int radix_tree_preload(gfp_t gfp_mask) > +{ > + /* Warn on non-sensical use... */ > + WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT)); > + return __radix_tree_preload(gfp_mask); > +} > EXPORT_SYMBOL(radix_tree_preload); > > /* > + * The same as above function, except we don't guarantee preloading happens. > + * We do it, if we decide it helps. On success, return zero with preemption > + * disabled. On error, return -ENOMEM with preemption not disabled. > + */ > +int radix_tree_maybe_preload(gfp_t gfp_mask) > +{ > + if (gfp_mask & __GFP_WAIT) > + return __radix_tree_preload(gfp_mask); > + /* Preloading doesn't help anything with this gfp mask, skip it */ > + preempt_disable(); > + return 0; > +} > +EXPORT_SYMBOL(radix_tree_maybe_preload); > + > +/* > * Return the maximum key which can be store into a stored > * radix tree with height HEIGHT. > */ -- ~Randy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org