linux-kernel - Re: [PATCH] [RFC] UBI: Implement Fastmap support

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Date:	Thu, 24 May 2012 11:22:00 +0300
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Richard Weinberger <richard@....at>
Cc:	Shmulik Ladkani <shmulik.ladkani@...il.com>,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Heinz.Egger@...utronix.de, tim.bird@...sony.com, tglx@...utronix.de
Subject: Re: [PATCH] [RFC] UBI: Implement Fastmap support

On Tue, 2012-05-22 at 18:55 +0200, Richard Weinberger wrote:
> >> +     * has never seen any PEB used by the original fastmap.
> >> +     */
> >> +    if (!e) {
> >> +            ubi_assert(ubi->old_fm);
> >> +            e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_ATOMIC);
> >
> > Must it be GFP_ATOMIC?
> 
> Yes. This function is called under a spinlock.

I did not look close, but this sounds bad.

You need to have a much better justification than "I allocate it under a
spinlock". You need to tell "... because there is no way or very
difficult to pre-allocate it while I do not have the spinlock held,
because ... (explanation)".

> 
-- 
Best Regards,
Artem Bityutskiy

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