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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: 86hmk6x3y4g61j7dy6pwtnzxfwu1q911 X-Rspamd-Queue-Id: 7D80D18000A X-Rspamd-Server: rspam09 X-HE-Tag: 1761668038-991955 X-HE-Meta: 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 NMticnTJ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 28.10.25 17:05, Joao Martins wrote: > On 28/10/2025 15:39, Luiz Capitulino wrote: >> A reproducible crash occurs when enabling HVO on s390. The crash and the >> proposed fix were worked on an s390 KVM guest running on an older >> hypervisor, as I don't have access to an LPAR. However, the same >> issue should occur on bare-metal. >> >> Reproducer (it may take a few runs to trigger): >> >> # sysctl vm.hugetlb_optimize_vmemmap=1 >> # echo 1 > /proc/sys/vm/nr_hugepages >> # echo 0 > /proc/sys/vm/nr_hugepages >> >> Crash log: >> >> [ 52.340369] list_del corruption. prev->next should be 000000d382110008, but was 000000d7116d3880. (prev=000000d7116d3910) >> [ 52.340420] ------------[ cut here ]------------ >> [ 52.340424] kernel BUG at lib/list_debug.c:62! >> [ 52.340566] monitor event: 0040 ilc:2 [#1]SMP >> [ 52.340573] Modules linked in: ctcm fsm qeth ccwgroup zfcp scsi_transport_fc qdio dasd_fba_mod dasd_eckd_mod dasd_mod xfs ghash_s390 prng des_s390 libdes sha3_512_s390 sha3_256_s390 virtio_net virtio_blk net_failover sha_common failover dm_mirror dm_region_hash dm_log dm_mod paes_s390 crypto_engine pkey_cca pkey_ep11 zcrypt pkey_pckmo pkey aes_s390 >> [ 52.340606] CPU: 1 UID: 0 PID: 1672 Comm: root-rep2 Kdump: loaded Not tainted 6.18.0-rc3 #1 NONE >> [ 52.340610] Hardware name: IBM 3931 LA1 400 (KVM/Linux) >> [ 52.340611] Krnl PSW : 0704c00180000000 0000015710cda7fe (__list_del_entry_valid_or_report+0xfe/0x128) >> [ 52.340619] 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 >> [ 52.340622] Krnl GPRS: c0000000ffffefff 0000000100000027 000000000000006d 0000000000000000 >> [ 52.340623] 000000d7116d35d8 000000d7116d35d0 0000000000000002 000000d7116d39b0 >> [ 52.340625] 000000d7116d3880 000000d7116d3910 000000d7116d3910 000000d382110008 >> [ 52.340626] 000003ffac1ccd08 000000d7116d39b0 0000015710cda7fa 000000d7116d37d0 >> [ 52.340632] Krnl Code: 0000015710cda7ee: c020003e496f larl %r2,00000157114a3acc >> 0000015710cda7f4: c0e5ffd5280e brasl %r14,000001571077f810 >> #0000015710cda7fa: af000000 mc 0,0 >> >0000015710cda7fe: b9040029 lgr %r2,%r9 >> 0000015710cda802: c0e5ffe5e193 brasl %r14,0000015710996b28 >> 0000015710cda808: e34090080004 lg %r4,8(%r9) >> 0000015710cda80e: b9040059 lgr %r5,%r9 >> 0000015710cda812: b9040038 lgr %r3,%r8 >> [ 52.340643] Call Trace: >> [ 52.340645] [<0000015710cda7fe>] __list_del_entry_valid_or_report+0xfe/0x128 >> [ 52.340649] ([<0000015710cda7fa>] __list_del_entry_valid_or_report+0xfa/0x128) >> [ 52.340652] [<0000015710a30b2e>] hugetlb_vmemmap_restore_folios+0x96/0x138 >> [ 52.340655] [<0000015710a268ac>] update_and_free_pages_bulk+0x64/0x150 >> [ 52.340659] [<0000015710a26f8a>] set_max_huge_pages+0x4ca/0x6f0 >> [ 52.340662] [<0000015710a273ba>] hugetlb_sysctl_handler_common+0xea/0x120 >> [ 52.340665] [<0000015710a27484>] hugetlb_sysctl_handler+0x44/0x50 >> [ 52.340667] [<0000015710b53ffa>] proc_sys_call_handler+0x17a/0x280 >> [ 52.340672] [<0000015710a90968>] vfs_write+0x2c8/0x3a0 >> [ 52.340676] [<0000015710a90bd2>] ksys_write+0x72/0x100 >> [ 52.340679] [<00000157111483a8>] __do_syscall+0x150/0x318 >> [ 52.340682] [<0000015711153a5e>] system_call+0x6e/0x90 >> [ 52.340684] Last Breaking-Event-Address: >> [ 52.340684] [<000001571077f85c>] _printk+0x4c/0x58 >> [ 52.340690] Kernel panic - not syncing: Fatal exception: panic_on_oops >> >> This issue was introduced by commit f13b83fdd996 ("hugetlb: batch TLB >> flushes when freeing vmemmap"). Before that change, the HVO >> implementation called flush_tlb_kernel_range() each time a vmemmap >> PMD split and remapping was performed. The mentioned commit changed this >> to issue a few flush_tlb_all() calls after performing all remappings. >> >> However, on s390, flush_tlb_kernel_range() expands to >> __tlb_flush_kernel() while flush_tlb_all() is not implemented. As a >> result, we went from flushing the TLB for every remapping to no flushing >> at all. >> >> This commit fixes this by introducing vmemmap_flush_tlb_all(), which >> expands to __tlb_flush_kernel() on s390 and to flush_tlb_all() on other >> archs. >> >> Fixes: f13b83fdd996 ("hugetlb: batch TLB flushes when freeing vmemmap")> > Signed-off-by: Luiz Capitulino >> --- >> mm/hugetlb_vmemmap.c | 17 +++++++++++++---- >> 1 file changed, 13 insertions(+), 4 deletions(-) >> >> diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c >> index ba0fb1b6a5a8..5819a3088850 100644 >> --- a/mm/hugetlb_vmemmap.c >> +++ b/mm/hugetlb_vmemmap.c >> @@ -48,6 +48,15 @@ struct vmemmap_remap_walk { >> unsigned long flags; >> }; >> >> +static inline void vmemmap_flush_tlb_all(void) >> +{ >> +#ifdef CONFIG_S390 >> + __tlb_flush_kernel(); >> +#else >> + flush_tlb_all(); >> +#endif >> +} >> + > > Wouldn't a better fix be to implement flush_tlb_all() in > s390/include/asm/tlbflush.h since that aliases to __tlb_flush_kernel()? Agreed, that feels cleaner and avoids this ifdef here. -- Cheers David / dhildenb