On 25.07.19 11:22, Rafael J. Wysocki wrote: > On Thu, Jul 25, 2019 at 11:18 AM Oscar Salvador <osalvador@xxxxxxx> wrote: >> >> On Wed, Jul 24, 2019 at 04:30:17PM +0200, David Hildenbrand wrote: >>> We end up calling __add_memory() without the device hotplug lock held. >>> (I used a local patch to assert in __add_memory() that the >>> device_hotplug_lock is held - I might upstream that as well soon) >>> >>> [ 26.771684] create_memory_block_devices+0xa4/0x140 >>> [ 26.772952] add_memory_resource+0xde/0x200 >>> [ 26.773987] __add_memory+0x6e/0xa0 >>> [ 26.775161] acpi_memory_device_add+0x149/0x2b0 >>> [ 26.776263] acpi_bus_attach+0xf1/0x1f0 >>> [ 26.777247] acpi_bus_attach+0x66/0x1f0 >>> [ 26.778268] acpi_bus_attach+0x66/0x1f0 >>> [ 26.779073] acpi_bus_attach+0x66/0x1f0 >>> [ 26.780143] acpi_bus_scan+0x3e/0x90 >>> [ 26.780844] acpi_scan_init+0x109/0x257 >>> [ 26.781638] acpi_init+0x2ab/0x30d >>> [ 26.782248] do_one_initcall+0x58/0x2cf >>> [ 26.783181] kernel_init_freeable+0x1bd/0x247 >>> [ 26.784345] kernel_init+0x5/0xf1 >>> [ 26.785314] ret_from_fork+0x3a/0x50 >>> >>> So perform the locking just like in acpi_device_hotplug(). >>> >>> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> >>> Cc: Len Brown <lenb@xxxxxxxxxx >>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >>> Cc: Oscar Salvador <osalvador@xxxxxxx> >>> Cc: Michal Hocko <mhocko@xxxxxxxx> >>> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> >> >> Given that that call comes from a __init function, so while booting, I wonder >> how bad it is. > > Yes, it probably does not matter. It can at least confuse lockdep, but I agree that this is not stable material. > >> Anyway, let us be consistent: > > Right. > -- Thanks, David / dhildenb
