linux-kernel - [PATCH v2] mm: Check if section present during memory block (un)registering

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <1440565957-16520-1-git-send-email-yinghai@kernel.org>
Date:	Tue, 25 Aug 2015 22:12:37 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Tony Luck <tony.luck@...el.com>
Cc:	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>,
	stable@...r.kernel.org.#v3.15
Subject: [PATCH v2] mm: Check if section present during memory block (un)registering

Tony found on his setup, if memory block size 512M will cause crash
during booting.

 BUG: unable to handle kernel paging request at ffffea0074000020
 IP: [<ffffffff81670527>] get_nid_for_pfn+0x17/0x40
 PGD 128ffcb067 PUD 128ffc9067 PMD 0 
 Oops: 0000 [#1] SMP 
 Modules linked in:
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.2.0-rc8 #1
...
 Call Trace:
  [<ffffffff81453b56>] ? register_mem_sect_under_node+0x66/0xe0
  [<ffffffff81453eeb>] register_one_node+0x17b/0x240
  [<ffffffff81b1f1ed>] ? pci_iommu_alloc+0x6e/0x6e
  [<ffffffff81b1f229>] topology_init+0x3c/0x95
  [<ffffffff8100213d>] do_one_initcall+0xcd/0x1f0

The system has non continuous RAM address:
 BIOS-e820: [mem 0x0000001300000000-0x0000001cffffffff] usable
 BIOS-e820: [mem 0x0000001d70000000-0x0000001ec7ffefff] usable
 BIOS-e820: [mem 0x0000001f00000000-0x0000002bffffffff] usable
 BIOS-e820: [mem 0x0000002c18000000-0x0000002d6fffefff] usable
 BIOS-e820: [mem 0x0000002e00000000-0x00000039ffffffff] usable

So there are start sections in memory block not present.
For example:
memory block : [0x2c18000000, 0x2c20000000) 512M
first three sections are not present.

Current register_mem_sect_under_node() assume first section is present,
but memory block section number range [start_section_nr, end_section_nr]
would include not present section.

For arch that support vmemmap, we don't setup memmap for struct page area
within not present sections area.

So skip the pfn range that belong to absent section.

Also fixes unregister_mem_sect_under_nodes() that assume one section per
memory block.

Reported-by: Tony Luck <tony.luck@...el.com>
Tested-by: Tony Luck <tony.luck@...el.com>
Fixes: bdee237c0343 ("x86: mm: Use 2GB memory block size on large memory x86-64 systems")
Fixes: 982792c782ef ("x86, mm: probe memory block size for generic x86 64bit")
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Cc: stable@...r.kernel.org #v3.15

---
-v2: add fixes and comment.
---

 drivers/base/node.c |   31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

Index: linux-2.6/drivers/base/node.c
===================================================================
--- linux-2.6.orig/drivers/base/node.c
+++ linux-2.6/drivers/base/node.c
@@ -390,7 +390,18 @@ int register_mem_sect_under_node(struct
 	sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
 	sect_end_pfn += PAGES_PER_SECTION - 1;
 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
-		int page_nid;
+		int page_nid, scn_nr;
+
+		/*
+		 * memory block could have several absent sections from start.
+		 * skip pfn range from absent section
+		 */
+		scn_nr = pfn_to_section_nr(pfn);
+		if (!present_section_nr(scn_nr)) {
+			pfn = round_down(pfn + PAGES_PER_SECTION,
+					 PAGES_PER_SECTION) - 1;
+			continue;
+		}
 
 		page_nid = get_nid_for_pfn(pfn);
 		if (page_nid < 0)
@@ -426,10 +437,22 @@ int unregister_mem_sect_under_nodes(stru
 		return -ENOMEM;
 	nodes_clear(*unlinked_nodes);
 
-	sect_start_pfn = section_nr_to_pfn(phys_index);
-	sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
+	sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
+	sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
+	sect_end_pfn += PAGES_PER_SECTION - 1;
 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
-		int nid;
+		int nid, scn_nr;
+
+		/*
+		 * memory block could have several absent sections from start.
+		 * skip pfn range from absent section
+		 */
+		scn_nr = pfn_to_section_nr(pfn);
+		if (!present_section_nr(scn_nr)) {
+			pfn = round_down(pfn + PAGES_PER_SECTION,
+					 PAGES_PER_SECTION) - 1;
+			continue;
+		}
 
 		nid = get_nid_for_pfn(pfn);
 		if (nid < 0)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/