linux-kernel - Re: [PATCH RESEND v2 5/6] mm/page_alloc: forward the gfp flags from alloc_contig_range() to post_alloc

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Message-ID: <Z1Aa3SjgMCS59agm@localhost.localdomain>
Date: Wed, 4 Dec 2024 10:03:25 +0100
From: Oscar Salvador <osalvador@...e.de>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linuxppc-dev@...ts.ozlabs.org,
	Andrew Morton <akpm@...ux-foundation.org>, Zi Yan <ziy@...dia.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>
Subject: Re: [PATCH RESEND v2 5/6] mm/page_alloc: forward the gfp flags from
 alloc_contig_range() to post_alloc_hook()

On Tue, Dec 03, 2024 at 10:47:31AM +0100, David Hildenbrand wrote:
> In the __GFP_COMP case, we already pass the gfp_flags to
> prep_new_page()->post_alloc_hook(). However, in the !__GFP_COMP case, we
> essentially pass only hardcoded __GFP_MOVABLE to post_alloc_hook(),
> preventing some action modifiers from being effective..
> 
> Let's pass our now properly adjusted gfp flags there as well.
> 
> This way, we can now support __GFP_ZERO for alloc_contig_*().
> 
> As a side effect, we now also support __GFP_SKIP_ZERO and__GFP_ZEROTAGS;
> but we'll keep the more special stuff (KASAN, NOLOCKDEP) disabled for
> now.
> 
> It's worth noting that with __GFP_ZERO, we might unnecessarily zero pages
> when we have to release part of our range using free_contig_range() again.
> This can be optimized in the future, if ever required; the caller we'll
> be converting (powernv/memtrace) next won't trigger this.
> 
> Signed-off-by: David Hildenbrand <david@...hat.com>

Reviewed-by: Oscar Salvador <osalvador@...e.de>


-- 
Oscar Salvador
SUSE Labs