6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michael Roth <michael.roth@xxxxxxx>
[ Upstream commit 01b1e3ca0e5ce47bbae8217d47376ad01b331b07 ]
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@xxxxxxx/T/#me2eceb9906fcae5fe958b3fe88e41f920f8335b6
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 135278ddaf627..79fb687bb90f9 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;
--
2.42.0
