Upstream MGLRU fix reference (for Ubuntu backport consideration) I investigated whether the upstream patches for a similar MGLRU list_del corruption race apply to this report. Summary for the kernel team:
--- Related upstream work (LKML / Patchew, August 2026) --- 1) v1 (2026-08-07, Qualcomm) — NOT suitable "mm/mglru: fix lockless folio_putback_lru() race in evict_folios()" Wraps folio_putback_lru() with spin_lock_irq(&lruvec->lru_lock). Symptoms match our initial kdump (list_del corruption @ lib/list_debug.c:64, lru_gen_del_folio, kswapd). However syzbot/reviewers reported self-deadlock: folio_putback_lru() must not be called while holding lru_lock. LKML: https://lists.openwall.net/linux-kernel/2026/08/07/843 2) v2 (2026-08-12, Kairui Song / Tencent) — likely real fix "mm/mglru: fix and remove redundant unevictable folio handling" Removes unevictable shortcuts in sort_folio() and evict_folios(); routes unevictable folios through move_folios_to_lru() instead (avoids lock-order issues and incorrect lru_gen_del_folio use / mlock_count corruption). Patchew: https://patchew.org/linux/[email protected]/ LKML: https://lkml.iu.edu/2608.1/05013.html Discussion suggests targeting the Linux 7.3 cycle. --- Relevance to this bug (#2162722) --- Our earliest crashes (2026-08-03, 2026-08-09) hit lru_gen_del_folio directly — the same function implicated in the v2 patch series. Later recurrences (Aug 23–Sep 1) also remain in kernel MM / page-cache paths (lru_activate, __page_cache_release, __handle_mm_fault) even with MGLRU disabled via sysfs (lru_gen/enabled = 0x0000). I could not find mglru/evict_folio fix entries in the Debian changelog for linux-image-7.0.0-31-generic (installed 2026-09-04 via unattended-upgrade). Request: when backporting MGLRU fixes to the Ubuntu 7.0 series, please consider the v2 approach (not the v1 spin_lock wrapper). Happy to test pre-release kernels. Host: Ubuntu 26.04.1 LTS, linux-image-7.0.0-31-generic, MGLRU disabled (0x0000). -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2162722 Title: general protection fault in lru_gen_del_folio during exit_mmap (ThreadPoolForeg) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2162722/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
