| Message ID | 20231103142650.108394-1-michael.roth@amd.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | efi/unaccepted: Fix off-by-one when checking for overlapping ranges | expand |
On Fri, Nov 03, 2023 at 09:26:50AM -0500, Michael Roth wrote: > When a thread needs to accept memory it will scan the accepting_list > to see if any ranges already being processed by other threads overlap > with its range. Due to an off-by-one in the range comparisons, a thread > might falsely determine that an overlapping range is being accepted, > leading to an unnecessary delay before it begins processing the range. Maybe s/thread/task/g ? > 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 > Signed-off-by: Michael Roth <michael.roth@amd.com> Otherwise, looks good: Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> >
On Fri, Nov 03, 2023 at 05:53:53PM +0300, Kirill A . Shutemov wrote: > On Fri, Nov 03, 2023 at 09:26:50AM -0500, Michael Roth wrote: > > When a thread needs to accept memory it will scan the accepting_list > > to see if any ranges already being processed by other threads overlap > > with its range. Due to an off-by-one in the range comparisons, a thread > > might falsely determine that an overlapping range is being accepted, > > leading to an unnecessary delay before it begins processing the range. > > Maybe s/thread/task/g ? > > > 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 > > Signed-off-by: Michael Roth <michael.roth@amd.com> > > Otherwise, looks good: > > Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Thanks! Sending a v2 with suggested changes. -Mike > > > > -- > Kiryl Shutsemau / Kirill A. Shutemov
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;
When a thread needs to accept memory it will scan the accepting_list to see if any ranges already being processed by other threads overlap with its range. Due to an off-by-one in the range comparisons, a thread 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 Signed-off-by: Michael Roth <michael.roth@amd.com> --- drivers/firmware/efi/unaccepted_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)