linux-kernel - Re: [PATCH v2 2/2] mm/vmalloc: Print a warning message first on failure

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Message-ID: <YJg8QO2JXm0+8UH6@casper.infradead.org>
Date:   Sun, 9 May 2021 20:47:12 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Mel Gorman <mgorman@...e.de>, Hillf Danton <hdanton@...a.com>,
        Michal Hocko <mhocko@...e.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH v2 2/2] mm/vmalloc: Print a warning message first on
 failure

On Sun, May 09, 2021 at 09:38:44PM +0200, Uladzislau Rezki (Sony) wrote:
>  export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
> -			      -O2 -fomit-frame-pointer -std=gnu89
> +			      -O0 -g -fomit-frame-pointer -std=gnu89

You clearly didn't intend to submit this portion ...

> +++ b/mm/vmalloc.c
> @@ -2781,11 +2781,11 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
>  	}
>  
>  	if (!area->pages) {
> -		free_vm_area(area);
>  		warn_alloc(gfp_mask, NULL,
>  			   "vmalloc size %lu allocation failure: "
>  			   "page array size %lu allocation failed",
>  			   nr_small_pages * PAGE_SIZE, array_size);
> +		free_vm_area(area);
>  		return NULL;
>  	}

I think this is a bad idea.  We're clearly low on memory (a memory
allocation just failed).  We should free the memory we have allocated
to improve the chances of the warning message making it out.