linux-kernel - Re: [PATCH 2/3] uprobes: change build_map_info() to try kmalloc(GFP

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Message-ID: <20120605101047.GA8822@redhat.com>
Date:	Tue, 5 Jun 2012 12:10:47 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] uprobes: change build_map_info() to try
	kmalloc(GFP_NOWAIT) first

On 06/04, Oleg Nesterov wrote:
>
> @@ -772,8 +772,13 @@ build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
>  			continue;
>
>  		if (!prev) {
> -			more++;
> -			continue;
> +			prev = kmalloc(sizeof(struct map_info),
> +					GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN);
> +			if (!prev) {
> +				more++;
> +				continue;
> +			}
> +			prev->next = NULL;
>  		}

OK, this is not exactly right, it is pointless and wrong to
do kmalloc(GFP_NOWAIT) if it failed before (iow, more != 0).

Easy to fix, I'll send v2 tomorrow.

Oleg.

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