linux-kernel - [PATCH 5.10 196/289] ARC: mm: Use max_high

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

Date:   Mon, 17 May 2021 16:02:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vladimir Isaev <isaev@...opsys.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Vineet Gupta <vgupta@...opsys.com>
Subject: [PATCH 5.10 196/289] ARC: mm: Use max_high_pfn as a HIGHMEM zone border

From: Vladimir Isaev <isaev@...opsys.com>

commit 1d5e4640e5df15252398c1b621f6bd432f2d7f17 upstream.

Commit 4af22ded0ecf ("arc: fix memory initialization for systems
with two memory banks") fixed highmem, but for the PAE case it causes
bug messages:

| BUG: Bad page state in process swapper  pfn:80000
| page:(ptrval) refcount:0 mapcount:1 mapping:00000000 index:0x0 pfn:0x80000 flags: 0x0()
| raw: 00000000 00000100 00000122 00000000 00000000 00000000 00000000 00000000
| raw: 00000000
| page dumped because: nonzero mapcount
| Modules linked in:
| CPU: 0 PID: 0 Comm: swapper Not tainted 5.12.0-rc5-00003-g1e43c377a79f #1

This is because the fix expects highmem to be always less than
lowmem and uses min_low_pfn as an upper zone border for highmem.

max_high_pfn should be ok for both highmem and highmem+PAE cases.

Fixes: 4af22ded0ecf ("arc: fix memory initialization for systems with two memory banks")
Signed-off-by: Vladimir Isaev <isaev@...opsys.com>
Cc: Mike Rapoport <rppt@...ux.ibm.com>
Cc: stable@...r.kernel.org  #5.8 onwards
Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/arc/mm/init.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -158,7 +158,16 @@ void __init setup_arch_memory(void)
 	min_high_pfn = PFN_DOWN(high_mem_start);
 	max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);
 
-	max_zone_pfn[ZONE_HIGHMEM] = min_low_pfn;
+	/*
+	 * max_high_pfn should be ok here for both HIGHMEM and HIGHMEM+PAE.
+	 * For HIGHMEM without PAE max_high_pfn should be less than
+	 * min_low_pfn to guarantee that these two regions don't overlap.
+	 * For PAE case highmem is greater than lowmem, so it is natural
+	 * to use max_high_pfn.
+	 *
+	 * In both cases, holes should be handled by pfn_valid().
+	 */
+	max_zone_pfn[ZONE_HIGHMEM] = max_high_pfn;
 
 	high_memory = (void *)(min_high_pfn << PAGE_SHIFT);
 	kmap_init();