From: Michael Roth <michael.roth@amd.com>
To: <linux-efi@vger.kernel.org>
Cc: <x86@kernel.org>, <linux-coco@lists.linux.dev>,
<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
Ard Biesheuvel <ardb@kernel.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Nikolay Borisov <nik.borisov@suse.com>, <stable@kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: [PATCH v2] efi/unaccepted: Fix off-by-one when checking for overlapping ranges
Date: Fri, 3 Nov 2023 10:13:54 -0500 [thread overview]
Message-ID: <20231103151354.110636-1-michael.roth@amd.com> (raw)
When a task needs to accept memory it will scan the accepting_list
to see if any ranges already being processed by other tasks overlap
with its range. Due to an off-by-one in the range comparisons, a task
might falsely determine that an overlapping range is being accepted,
leading to an unnecessary delay before it begins processing the range.
Fix the off-by-one in the range comparison to prevent this and slightly
improve performance.
Fixes: 50e782a86c98 ("efi/unaccepted: Fix soft lockups caused by parallel memory acceptance")
Link: https://lore.kernel.org/linux-mm/20231101004523.vseyi5bezgfaht5i@amd.com/T/#me2eceb9906fcae5fe958b3fe88e41f920f8335b6
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
v2:
* Improve commit message terminology (Kirill)
---
drivers/firmware/efi/unaccepted_memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/efi/unaccepted_memory.c
index 135278ddaf62..79fb687bb90f 100644
--- a/drivers/firmware/efi/unaccepted_memory.c
+++ b/drivers/firmware/efi/unaccepted_memory.c
@@ -100,7 +100,7 @@ void accept_memory(phys_addr_t start, phys_addr_t end)
* overlap on physical address level.
*/
list_for_each_entry(entry, &accepting_list, list) {
- if (entry->end < range.start)
+ if (entry->end <= range.start)
continue;
if (entry->start >= range.end)
continue;
--
2.25.1
next reply other threads:[~2023-11-03 15:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-03 15:13 Michael Roth [this message]
2023-11-03 15:30 ` [PATCH v2] efi/unaccepted: Fix off-by-one when checking for overlapping ranges Vlastimil Babka
2023-11-08 11:21 ` Ard Biesheuvel
2023-11-28 11:25 ` Vlastimil Babka
2023-11-28 11:50 ` Ard Biesheuvel
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