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McKenney" , Steven Rostedt , Masami Hiramatsu , Dennis Zhou , Tejun Heo , Christoph Lameter , Martin Liu , David Rientjes , christian.koenig@amd.com, Shakeel Butt , SeongJae Park , Michal Hocko , Johannes Weiner , Sweet Tea Dorminy , Lorenzo Stoakes , "Liam R . 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X-MS-Exchange-Transport-CrossTenantHeadersStamped: YQXPR01MB6686 On 2026-02-26 07:04, Heiko Carstens wrote: > On Tue, Feb 17, 2026 at 11:10:03AM -0500, Mathieu Desnoyers wrote: >> This series introduces the hierarchical tree counter (hpcc) to increase >> accuracy of approximated RSS counters exposed through proc interfaces. >> >> With a test program hopping across CPUs doing frequent mmap/munmap >> operations, the upstream implementation approximation reaches a 1GB >> delta from the precise value after a few minutes, compared to a 80MB >> delta with the hierarchical counter. The hierarchical counter provides a >> guaranteed maximum approximation inaccuracy of 192MB on that hardware >> topology. >> >> This series is based on >> commit 0f2acd3148e0 Merge tag 'm68knommu-for-v7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu >> >> The main changes since v16: >> - Dropped OOM killer 2-pass task selection algorithm. >> - Introduce Kunit tests. >> - Only perform atomic increments of intermediate tree nodes when >> bits which are significant for carry propagation are being changed. > > This seems to cause crashes with linux-next on s390, at least I could bisect > it to the last patch of this series. Reverting the last one, makes the crashes > go away: > > 0acac6604c1cfd7a1762901f0a4abe87cf3a8619 is the first bad commit > commit 0acac6604c1cfd7a1762901f0a4abe87cf3a8619 (HEAD) > Author: Mathieu Desnoyers > AuthorDate: Tue Feb 17 11:10:06 2026 -0500 > Commit: Andrew Morton > CommitDate: Tue Feb 24 11:15:15 2026 -0800 > > mm: improve RSS counter approximation accuracy for proc interfaces > > Unable to handle kernel pointer dereference in virtual kernel address space > Failing address: 766d615f72615000 TEID: 766d615f72615803 ESOP-2 FSI > Fault in home space mode while using kernel ASCE. > AS:000000025dc04007 R3:0000000000000024 > Oops: 0038 ilc:2 [#1]SMP > Modules linked in: > CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.0.0-20260224.rc1.git266.3ef088b0c577.300.fc43.s390x+next #1 PREEMPTLAZY > Hardware name: IBM 3931 A01 703 (z/VM 7.4.0) > Krnl PSW : 0704c00180000000 00000216ef164cde (kernfs_name_hash+0x1e/0xb0) > R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 > Krnl GPRS: 0000000000000000 0000000000000000 766d615f72615f65 0000000000000000 > 766d615f72615f65 0000000000000000 0000000000000000 0000000000000000 > 766d615f72615f65 0000000081212440 0000000000000000 0000000000000000 > 0000000080a00000 00000216efcb5390 00000216ef16530c 00000196eeb07ae0 > Krnl Code: 00000216ef164cd2: a7190000 lghi %r1,0 > 00000216ef164cd6: b9040042 lgr %r4,%r2 > *00000216ef164cda: a7090000 lghi %r0,0 > >00000216ef164cde: b25e0014 srst %r1,%r4 > 00000216ef164ce2: a714fffe brc 1,00000216ef164cde > 00000216ef164ce6: b9e92051 sgrk %r5,%r1,%r2 > 00000216ef164cea: ec1200208076 crj %r1,%r2,8,00000216ef164d2a > 00000216ef164cf0: b9160005 llgfr %r0,%r5 > Call Trace: > [<00000216ef164cde>] kernfs_name_hash+0x1e/0xb0 > [<00000216ef167d32>] kernfs_remove_by_name_ns+0x72/0x120 > [<00000216ef16bbfa>] remove_files+0x4a/0x90 > [<00000216ef16bf96>] create_files+0x276/0x2b0 > [<00000216ef16c15a>] internal_create_group+0x18a/0x320 > [<00000216f09b61c6>] swap_init+0x5e/0xa0 > [<00000216eec7fb00>] do_one_initcall+0x40/0x270 > [<00000216f0990a40>] kernel_init_freeable+0x2b0/0x330 > [<00000216efb5160e>] kernel_init+0x2e/0x180 > [<00000216eec81ffc>] __ret_from_fork+0x3c/0x240 > [<00000216efb5e052>] ret_from_fork+0xa/0x30 > Last Breaking-Event-Address: > [<00000216ef165306>] kernfs_find_ns+0x76/0x140 > Kernel panic - not syncing: Fatal exception: panic_on_oops It looks like either an issue with ordering of the bootup sequence, or an issue with the size of struct mm_struct init_mm. I'll have a look. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com