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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: dan.j.williams@intel.com, akpm@linux-foundation.org,
	David Hildenbrand <david@redhat.com>
Cc: linux-mm@kvack.org,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	linux-nvdimm@lists.01.org
Subject: [PATCH 1/2] mm/memunmap: Use the correct start and end pfn when removing pages from zone
Date: Thu, 26 Sep 2019 17:55:51 +0530
Message-ID: <20190926122552.17905-1-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20190830091428.18399-1-david@redhat.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

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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 [this message]
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
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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