This is a note to let you know that I've just added the patch titled
PCI: Fix resource double counting on remove & rescan
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-fix-resource-double-counting-on-remove-rescan.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 65cb9bfcb75323a840e208cfbc3677554e250c43
Author: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Date: Tue May 7 13:25:16 2024 +0300
PCI: Fix resource double counting on remove & rescan
[ Upstream commit 903534fa7d30214d8ba840ab1cd9e917e0c88e41 ]
pbus_size_mem() keeps the size of the optional resources in
children_add_size. When calculating the PCI bridge window size,
calculate_memsize() lower bounds size by old_size before adding
children_add_size and performing the window size alignment. This
results in double counting for the resources in children_add_size
because old_size may be based on the previous size of the bridge
window after it has already included children_add_size (that is,
size1 in pbus_size_mem() from an earlier invocation of that
function).
As a result, on repeated remove of the bus & rescan cycles the resource
size keeps increasing when children_add_size is non-zero as can be seen
from this extract:
iomem0: 23fffd00000-23fffdfffff : PCI Bus 0000:03 # 1MiB
iomem1: 20000000000-200001fffff : PCI Bus 0000:03 # 2MiB
iomem2: 20000000000-200002fffff : PCI Bus 0000:03 # 3MiB
iomem3: 20000000000-200003fffff : PCI Bus 0000:03 # 4MiB
iomem4: 20000000000-200004fffff : PCI Bus 0000:03 # 5MiB
Solve the double counting by moving old_size check later in
calculate_memsize() so that children_add_size is already accounted for.
After the patch, the bridge window retains its size as expected:
iomem0: 23fffd00000-23fffdfffff : PCI Bus 0000:03 # 1MiB
iomem1: 20000000000-200000fffff : PCI Bus 0000:03 # 1MiB
iomem2: 20000000000-200000fffff : PCI Bus 0000:03 # 1MiB
Fixes: a4ac9fea016f ("PCI : Calculate right add_size")
Link: https://lore.kernel.org/r/20240507102523.57320-2-ilpo.jarvinen@xxxxxxxxxxxxxxx
Tested-by: Lidong Wang <lidong.wang@xxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 16d291e10627b..a159bfdfa2512 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -824,11 +824,9 @@ static resource_size_t calculate_memsize(resource_size_t size,
size = min_size;
if (old_size == 1)
old_size = 0;
- if (size < old_size)
- size = old_size;
- size = ALIGN(max(size, add_size) + children_add_size, align);
- return size;
+ size = max(size, add_size) + children_add_size;
+ return ALIGN(max(size, old_size), align);
}
resource_size_t __weak pcibios_window_alignment(struct pci_bus *bus,
