On 06.10.22 17:35, Uladzislau Rezki wrote:
Hi,
we're currently hitting a weird vmap issue in debug kernels with KASAN enabled
on fairly large VMs. I reproduced it on v5.19 (did not get the chance to
try 6.0 yet because I don't have access to the machine right now, but
I suspect it persists).
It seems to trigger when udev probes a massive amount of devices in parallel
while the system is booting up. Once the system booted, I no longer see any
such issues.
[ 165.818200] vmap allocation for size 2498560 failed: use vmalloc=<size> to increase size
[ 165.836622] vmap allocation for size 315392 failed: use vmalloc=<size> to increase size
[ 165.837461] vmap allocation for size 315392 failed: use vmalloc=<size> to increase size
[ 165.840573] vmap allocation for size 2498560 failed: use vmalloc=<size> to increase size
[ 165.841059] vmap allocation for size 2498560 failed: use vmalloc=<size> to increase size
[ 165.841428] vmap allocation for size 2498560 failed: use vmalloc=<size> to increase size
[ 165.841819] vmap allocation for size 2498560 failed: use vmalloc=<size> to increase size
[ 165.842123] vmap allocation for size 2498560 failed: use vmalloc=<size> to increase size
[ 165.843359] vmap allocation for size 2498560 failed: use vmalloc=<size> to increase size
[ 165.844894] vmap allocation for size 2498560 failed: use vmalloc=<size> to increase size
[ 165.847028] CPU: 253 PID: 4995 Comm: systemd-udevd Not tainted 5.19.0 #2
[ 165.935689] Hardware name: Lenovo ThinkSystem SR950 -[7X12ABC1WW]-/-[7X12ABC1WW]-, BIOS -[PSE130O-1.81]- 05/20/2020
[ 165.947343] Call Trace:
[ 165.950075] <TASK>
[ 165.952425] dump_stack_lvl+0x57/0x81
[ 165.956532] warn_alloc.cold+0x95/0x18a
[ 165.960836] ? zone_watermark_ok_safe+0x240/0x240
[ 165.966100] ? slab_free_freelist_hook+0x11d/0x1d0
[ 165.971461] ? __get_vm_area_node+0x2af/0x360
[ 165.976341] ? __get_vm_area_node+0x2af/0x360
[ 165.981219] __vmalloc_node_range+0x291/0x560
[ 165.986087] ? __mutex_unlock_slowpath+0x161/0x5e0
[ 165.991447] ? move_module+0x4c/0x630
[ 165.995547] ? vfree_atomic+0xa0/0xa0
[ 165.999647] ? move_module+0x4c/0x630
[ 166.003741] module_alloc+0xe7/0x170
[ 166.007747] ? move_module+0x4c/0x630
[ 166.011840] move_module+0x4c/0x630
[ 166.015751] layout_and_allocate+0x32c/0x560
[ 166.020519] load_module+0x8e0/0x25c0
Can it be that we do not have enough "module section" size? I mean the
section size, which is MODULES_END - MODULES_VADDR is rather small so
some modules are not loaded due to no space.
CONFIG_RANDOMIZE_BASE also creates some offset overhead if enabled on
your box. But it looks it is rather negligible.
Right, I suspected both points -- but was fairly confused why the
numbers of CPUs would matter.
What would make sense is that if we're tight on module vmap space, that
the race I think that could happen with purging only once and then
failing could become relevant.
Maybe try to increase the module-section size to see if it solves the
problem.
What would be the easiest way to do that?
Thanks!
--
Thanks,
David / dhildenb
