linux-kernel - Re: [PATCH] Revert "mm/page_alloc: make should_fail_alloc

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Message-ID: <20210705113723.GN3840@techsingularity.net>
Date:   Mon, 5 Jul 2021 12:37:23 +0100
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Marco Elver <elver@...gle.com>
Cc:     akpm@...ux-foundation.org, glider@...gle.com, dvyukov@...gle.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kasan-dev@...glegroups.com, Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Vlastimil Babka <vbabka@...e.cz>,
        Yang Shi <shy828301@...il.com>, bpf@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>
Subject: Re: [PATCH] Revert "mm/page_alloc: make should_fail_alloc_page()
 static"

On Mon, Jul 05, 2021 at 12:38:06PM +0200, Marco Elver wrote:
> This reverts commit f7173090033c70886d925995e9dfdfb76dbb2441.
> 
> Commit 76cd61739fd1 ("mm/error_inject: Fix allow_error_inject function
> signatures") explicitly made should_fail_alloc_page() non-static, due to
> worries of remaining compiler optimizations in the absence of function
> side-effects while being noinline.
> 
> Furthermore, kernel/bpf/verifier.c pushes should_fail_alloc_page onto
> the btf_non_sleepable_error_inject BTF IDs set, which when enabling
> CONFIG_DEBUG_INFO_BTF results in an error at the BTFIDS stage:
> 
>   FAILED unresolved symbol should_fail_alloc_page
> 
> To avoid the W=1 warning, add a function declaration right above the
> function itself, with a comment it is required in a BTF IDs set.
> 
> Fixes: f7173090033c ("mm/page_alloc: make should_fail_alloc_page() static")
> Cc: Mel Gorman <mgorman@...hsingularity.net>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Signed-off-by: Marco Elver <elver@...gle.com>

Acked-by: Mel Gorman <mgorman@...hsingularity.net>

Out of curiousity though, why does block/blk-core.c not require
something similar for should_fail_bio?

-- 
Mel Gorman
SUSE Labs