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From: Pankaj Gupta <pagupta@redhat.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: linux-mm@kvack.org, linux-nvdimm@lists.01.org,
	akpm@linux-foundation.org, David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH 1/2] mm/memunmap: Use the correct start and end pfn when removing pages from zone
Date: Thu, 26 Sep 2019 09:34:58 -0400 (EDT)
Message-ID: <327305557.3319542.1569504897998.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20190926122552.17905-1-aneesh.kumar@linux.ibm.com>


> 
> With altmap, all the resource pfns are not initialized. While initializing
> pfn, altmap reserve space is skipped. Hence when removing pfn from zone skip
> pfns that were never initialized.
> 
> Update memunmap_pages to calculate start and end pfn based on altmap
> values. This fixes a kernel crash that is observed when destroying namespace.
> 
> [   74.745056] BUG: Unable to handle kernel data access at 0xc00c000001400000
> [   74.745256] Faulting instruction address: 0xc0000000000b58b0
> cpu 0x2: Vector: 300 (Data Access) at [c00000026ea93580]
>     pc: c0000000000b58b0: memset+0x68/0x104
>     lr: c0000000003eb008: page_init_poison+0x38/0x50
>     ...
>   current = 0xc000000271c67d80
>   paca    = 0xc00000003fffd680   irqmask: 0x03   irq_happened: 0x01
>     pid   = 3665, comm = ndctl
> [link register   ] c0000000003eb008 page_init_poison+0x38/0x50
> [c00000026ea93830] c0000000004754d4 remove_pfn_range_from_zone+0x64/0x3e0
> [c00000026ea938a0] c0000000004b8a60 memunmap_pages+0x300/0x400
> [c00000026ea93930] c0000000009e32a0 devm_action_release+0x30/0x50
> ...
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
>  mm/memremap.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/memremap.c b/mm/memremap.c
> index 390bb3544589..76b98110031e 100644
> --- a/mm/memremap.c
> +++ b/mm/memremap.c
> @@ -113,7 +113,8 @@ static void dev_pagemap_cleanup(struct dev_pagemap
> *pgmap)
>  void memunmap_pages(struct dev_pagemap *pgmap)
>  {
>  	struct resource *res = &pgmap->res;
> -	unsigned long pfn = PHYS_PFN(res->start);
> +	unsigned long start_pfn, end_pfn;
> +	unsigned long pfn, nr_pages;
>  	int nid;
>  
>  	dev_pagemap_kill(pgmap);
> @@ -121,14 +122,18 @@ void memunmap_pages(struct dev_pagemap *pgmap)
>  		put_page(pfn_to_page(pfn));
>  	dev_pagemap_cleanup(pgmap);
>  
> +	start_pfn = pfn_first(pgmap);
> +	end_pfn = pfn_end(pgmap);
> +	nr_pages = end_pfn - start_pfn;
> +
>  	/* pages are dead and unused, undo the arch mapping */
> -	nid = page_to_nid(pfn_to_page(pfn));
> +	nid = page_to_nid(pfn_to_page(start_pfn));
>  
>  	mem_hotplug_begin();
> -	remove_pfn_range_from_zone(page_zone(pfn_to_page(pfn)), pfn,
> -				   PHYS_PFN(resource_size(res)));
> +	remove_pfn_range_from_zone(page_zone(pfn_to_page(start_pfn)),
> +				   start_pfn, nr_pages);
>  	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
> -		__remove_pages(pfn, PHYS_PFN(resource_size(res)), NULL);
> +		__remove_pages(start_pfn, nr_pages, NULL);
>  	} else {
>  		arch_remove_memory(nid, res->start, resource_size(res),
>  				pgmap_altmap(pgmap));
> --
> 2.21.0

Reviewed-by: Pankaj Gupta <pagupta@redhat.com>

> 
> 
> 
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  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190830091428.18399-1-david@redhat.com>
2019-09-26 12:25 ` Aneesh Kumar K.V
2019-09-26 12:25   ` [PATCH 2/2] mm/memmap_init: Update variable name in memmap_init_zone Aneesh Kumar K.V
2019-09-26 12:56     ` David Hildenbrand
2019-09-26 13:38     ` Pankaj Gupta
2019-09-26 12:43   ` [PATCH 1/2] mm/memunmap: Use the correct start and end pfn when removing pages from zone David Hildenbrand
2019-09-26 13:15     ` Aneesh Kumar K.V
2019-09-26 13:34   ` Pankaj Gupta [this message]
2019-09-26 22:45   ` Andrew Morton
2019-09-27  1:51     ` Aneesh Kumar K.V
2019-09-27  7:46       ` David Hildenbrand
2019-09-27 10:32         ` [PATCH] " Aneesh Kumar K.V
2019-09-27 10:38           ` David Hildenbrand
2019-09-27 10:36         ` [PATCH 1/2] " Aneesh Kumar K.V
2019-09-27 10:40           ` David Hildenbrand
2019-09-27 11:35             ` Aneesh Kumar K.V
2019-09-27 11:38               ` David Hildenbrand

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