Re: Intermittent storage (dm-crypt?) freeze - regression 6.4->6.5

[Matthew Wilcox <willy@infradead.org>]

On Fri, Oct 27, 2023 at 07:32:54PM +0200, Mikulas Patocka wrote:
> So, we got no reponse from the MM maintainers. Marek - please try this 

yes, how dare i go on holiday.  i'll look at this when i'm back.
probably.

> patch on all the machines where you hit the bug and if you still hit the 
> bug with this patch, report it.
> 
> Mikulas
> 
> 
> 
> From: Mikulas Patocka <mpatocka@redhat.com>
> Subject: [PATCH] dm-crypt: don't allocate large compound pages
> 
> It was reported that the patch 5054e778fcd9cd29ddaa8109077cd235527e4f94
> ("dm crypt: allocate compound pages if possible") causes intermittent
> freezes [1].
> 
> So far, it is not clear what is the root cause. It was reported that with
> the allocation order 3 or lower it works [1], so we restrict the order to
> 3 (that is PAGE_ALLOC_COSTLY_ORDER).
> 
> [1] https://www.spinics.net/lists/dm-devel/msg56048.html
> 
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Cc: stable@vger.kernel.org	# v6.5+
> Fixes: 5054e778fcd9 ("dm crypt: allocate compound pages if possible")
> 
> ---
>  drivers/md/dm-crypt.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: linux-2.6/drivers/md/dm-crypt.c
> ===================================================================
> --- linux-2.6.orig/drivers/md/dm-crypt.c
> +++ linux-2.6/drivers/md/dm-crypt.c
> @@ -1679,7 +1679,7 @@ static struct bio *crypt_alloc_buffer(st
>  	unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
>  	gfp_t gfp_mask = GFP_NOWAIT | __GFP_HIGHMEM;
>  	unsigned int remaining_size;
> -	unsigned int order = MAX_ORDER - 1;
> +	unsigned int order = PAGE_ALLOC_COSTLY_ORDER;
>  
>  retry:
>  	if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM))