| Message ID | da0fcd5e86c74239be79c7cb03651c0fce31b515.1676036673.git.geert+renesas@glider.be |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] PCI: Fix dropping valid root bus resources with .end = zero | expand |
On Fri, Feb 10, 2023 at 02:46:39PM +0100, Geert Uytterhoeven wrote: > On r8a7791/koelsch: > > kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak) > # cat /sys/kernel/debug/kmemleak > unreferenced object 0xc3a34e00 (size 64): > comm "swapper/0", pid 1, jiffies 4294937460 (age 199.080s) > hex dump (first 32 bytes): > b4 5d 81 f0 b4 5d 81 f0 c0 b0 a2 c3 00 00 00 00 .]...].......... > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > backtrace: > [<fe3aa979>] __kmalloc+0xf0/0x140 > [<34bd6bc0>] resource_list_create_entry+0x18/0x38 > [<767046bc>] pci_add_resource_offset+0x20/0x68 > [<b3f3edf2>] devm_of_pci_get_host_bridge_resources.constprop.0+0xb0/0x390 > > When coalescing two resources for a contiguous aperture, the second > resource is enlarged to cover the full contiguous range, while the > first resource is marked invalid. This invalidation is done by > clearing the flags, start, and end members. > > When adding the initial resources to the bus later, invalid resources > are skipped. Unfortunately, the check for an invalid resource considers > only the end member, causing false positives. > > E.g. on r8a7791/koelsch, root bus resource 0 ("bus 00") is skipped, and > no longer registered with pci_bus_insert_busn_res() (causing the memory > leak), nor printed: > > pci-rcar-gen2 ee090000.pci: host bridge /soc/pci@ee090000 ranges: > pci-rcar-gen2 ee090000.pci: MEM 0x00ee080000..0x00ee08ffff -> 0x00ee080000 > pci-rcar-gen2 ee090000.pci: PCI: revision 11 > pci-rcar-gen2 ee090000.pci: PCI host bridge to bus 0000:00 > -pci_bus 0000:00: root bus resource [bus 00] > pci_bus 0000:00: root bus resource [mem 0xee080000-0xee08ffff] > > Fix this by only skipping resources where all of the flags, start, and > end members are zero. > > Fixes: 7c3855c423b17f6c ("PCI: Coalesce host bridge contiguous apertures") > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > Tested-by: Niklas Schnelle <schnelle@linux.ibm.com> > Acked-by: Kai-Heng Feng <kai.heng.feng@canonical.com> Applied to pci/resource for v6.3, thanks! > --- > Is there any side effect of not registering the root bus resource with > pci_bus_insert_busn_res()? This is the resource created by > of_pci_parse_bus_range(), and thus affects any DT platforms using > "bus-range = <0 0>". > > Perhaps checking for "!res->flags" would be sufficient? > > I wonder if this still causes memory leaks on systems where resources > are coalesced, as the first resource of a contiguous aperture is no > longer referenced? Perhaps instead of clearing the resource, it should > be removed from the list (and freed? is it actually safe to do that?)? > - Bjorn thinks these would normally be freed via > __acpi_pci_root_release_info() (if the host bridge were > hot-removed), so probably not a leak since the invalidated resource > is still in the info->resources list and should be freed even though > it's been invalidated. > - Furthermore, Bjorn suspects it could probably be removed from the > list and freed here, and maybe even in the first loop when we > coalesce it, so we wouldn't have to check in the second loop. > > However, let's fix one bug at a time? This has been dragging on for > about half a year.... > > Apparently Johannes had identified the bug before, but didn't realize > the full impact... > https://lore.kernel.org/r/5331e942ff28bb191d62bb403b03ceb7d750856c.camel@sipsolutions.net/ > > v3: > - Actually the second resource is enlarged, and the first one is > invalidated, > > v2: > - Add Tested-by, Acked-by. > --- > drivers/pci/probe.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index 1779582fb5007cd1..5988584825482e9f 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -996,7 +996,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) > resource_list_for_each_entry_safe(window, n, &resources) { > offset = window->offset; > res = window->res; > - if (!res->end) > + if (!res->flags && !res->start && !res->end) > continue; > > list_move_tail(&window->node, &bridge->windows); > -- > 2.34.1 >
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 1779582fb5007cd1..5988584825482e9f 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -996,7 +996,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) resource_list_for_each_entry_safe(window, n, &resources) { offset = window->offset; res = window->res; - if (!res->end) + if (!res->flags && !res->start && !res->end) continue; list_move_tail(&window->node, &bridge->windows);
On r8a7791/koelsch: kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak) # cat /sys/kernel/debug/kmemleak unreferenced object 0xc3a34e00 (size 64): comm "swapper/0", pid 1, jiffies 4294937460 (age 199.080s) hex dump (first 32 bytes): b4 5d 81 f0 b4 5d 81 f0 c0 b0 a2 c3 00 00 00 00 .]...].......... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<fe3aa979>] __kmalloc+0xf0/0x140 [<34bd6bc0>] resource_list_create_entry+0x18/0x38 [<767046bc>] pci_add_resource_offset+0x20/0x68 [<b3f3edf2>] devm_of_pci_get_host_bridge_resources.constprop.0+0xb0/0x390 When coalescing two resources for a contiguous aperture, the second resource is enlarged to cover the full contiguous range, while the first resource is marked invalid. This invalidation is done by clearing the flags, start, and end members. When adding the initial resources to the bus later, invalid resources are skipped. Unfortunately, the check for an invalid resource considers only the end member, causing false positives. E.g. on r8a7791/koelsch, root bus resource 0 ("bus 00") is skipped, and no longer registered with pci_bus_insert_busn_res() (causing the memory leak), nor printed: pci-rcar-gen2 ee090000.pci: host bridge /soc/pci@ee090000 ranges: pci-rcar-gen2 ee090000.pci: MEM 0x00ee080000..0x00ee08ffff -> 0x00ee080000 pci-rcar-gen2 ee090000.pci: PCI: revision 11 pci-rcar-gen2 ee090000.pci: PCI host bridge to bus 0000:00 -pci_bus 0000:00: root bus resource [bus 00] pci_bus 0000:00: root bus resource [mem 0xee080000-0xee08ffff] Fix this by only skipping resources where all of the flags, start, and end members are zero. Fixes: 7c3855c423b17f6c ("PCI: Coalesce host bridge contiguous apertures") Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Tested-by: Niklas Schnelle <schnelle@linux.ibm.com> Acked-by: Kai-Heng Feng <kai.heng.feng@canonical.com> --- Is there any side effect of not registering the root bus resource with pci_bus_insert_busn_res()? This is the resource created by of_pci_parse_bus_range(), and thus affects any DT platforms using "bus-range = <0 0>". Perhaps checking for "!res->flags" would be sufficient? I wonder if this still causes memory leaks on systems where resources are coalesced, as the first resource of a contiguous aperture is no longer referenced? Perhaps instead of clearing the resource, it should be removed from the list (and freed? is it actually safe to do that?)? - Bjorn thinks these would normally be freed via __acpi_pci_root_release_info() (if the host bridge were hot-removed), so probably not a leak since the invalidated resource is still in the info->resources list and should be freed even though it's been invalidated. - Furthermore, Bjorn suspects it could probably be removed from the list and freed here, and maybe even in the first loop when we coalesce it, so we wouldn't have to check in the second loop. However, let's fix one bug at a time? This has been dragging on for about half a year.... Apparently Johannes had identified the bug before, but didn't realize the full impact... https://lore.kernel.org/r/5331e942ff28bb191d62bb403b03ceb7d750856c.camel@sipsolutions.net/ v3: - Actually the second resource is enlarged, and the first one is invalidated, v2: - Add Tested-by, Acked-by. --- drivers/pci/probe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)