>
> 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@xxxxxxxxxxxxx>
> ---
> 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@xxxxxxxxxx>
>
>
>
