b93af2cc8e
DAMON's virtual address space operation set implementation (vaddr) calls
pte_offset_map_lock() inside the page table walk callback function. This
is for reading and writing page table accessed bits. If
pte_offset_map_lock() fails, it retries by returning the page table walk
callback function with ACTION_AGAIN.
pte_offset_map_lock() can continuously fail if the target is a pmd
migration entry, though. Hence it could cause an infinite page table walk
if the migration cannot be done until the page table walk is finished.
This indeed caused a soft lockup when CPU hotplugging and DAMON were
running in parallel.
Avoid the infinite loop by simply not retrying the page table walk. DAMON
is promising only a best-effort accuracy, so missing access to such pages
is no problem.
Link: https://lkml.kernel.org/r/20250930004410.55228-1-sj@kernel.org
Fixes:
|
||
|---|---|---|
| .. | ||
| tests | ||
| Kconfig | ||
| Makefile | ||
| core.c | ||
| lru_sort.c | ||
| modules-common.c | ||
| modules-common.h | ||
| ops-common.c | ||
| ops-common.h | ||
| paddr.c | ||
| reclaim.c | ||
| stat.c | ||
| sysfs-common.c | ||
| sysfs-common.h | ||
| sysfs-schemes.c | ||
| sysfs.c | ||
| vaddr.c | ||