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To: Caleb Sander Mateos , Ming Lei Cc: Changhui Zhong , Linux Block Devices , linuxppc-dev@lists.ozlabs.org References: Content-Language: fr-FR From: "Christophe Leroy (CS GROUP)" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 26/02/2026 à 17:59, Caleb Sander Mateos a écrit : > On Thu, Feb 26, 2026 at 4:44 AM Ming Lei wrote: >> >> On Thu, Feb 26, 2026 at 6:48 PM Ming Lei wrote: >>> >>> Hi Changhui, >>> >>> Thanks for the report! >>> >>> Loop Caleb Sander Mateos in. >>> >>> Thanks, >>> >>> On Thu, Feb 26, 2026 at 6:37 PM Changhui Zhong wrote: >>>> >>>> Hello, >>>> >>>> on the ppc64le arch, I hit the issue below with ublksrv on the latest >>>> linux-block/for-next, please help check it, and let me know if you >>>> need any info/test for it. Thanks. >>>> >>>> INFO: HEAD of cloned kernel >>>> commit 37a43fd770f3dcac8f72f3ea909b3e893e2385c9 >>>> Merge: 13cd9b41227a c1dfbd7e71b0 >>>> Author: Jens Axboe >>>> Date: Wed Feb 25 08:37:06 2026 -0700 >>>> >>>> Merge branch 'for-7.1/block' into for-next >>>> >>>> * for-7.1/block: >>>> ublk: report BLK_SPLIT_INTERVAL_CAPABLE >>>> >>>> reproducer: >>>> compile and install https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fublk-org%2Fublksrv.git&data=05%7C02%7Cchristophe.leroy2%40cs-soprasteria.com%7Cf0b0066758be476be95508de75587a73%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639077220067774377%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=ki4yUMx%2FBTANcpfzEoVMdBKsuflIbzhHO2Wqpxtvj5g%3D&reserved=0 >>>> #echo 0 > /proc/sys/kernel/io_uring_disabled >>>> #modprobe ublk_drv >>>> #cd ublksrv >>>> #make test T=null >>>> #make test T=loop >>>> >>>> dmesg log： >>>> Feb 26 00:24:30 ibm-p9z-27-lp26 journal: running null/002 >>>> Feb 26 00:24:30 ibm-p9z-27-lp26 ublksrvd-0[57921]: start ublksrv io >>>> daemon ublksrvd-0 >>>> Feb 26 00:24:30 ibm-p9z-27-lp26 ublksrvd-0[57921]: tid 57923: ublk dev >>>> 0 queue 0 started >>>> Feb 26 00:24:30 ibm-p9z-27-lp26 ublksrvd-0[57921]: tid 57924: ublk dev >>>> 0 queue 1 started >>>> Feb 26 00:24:36 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083476.4882] platform-linux: do-add-ip6-address[2: >>>> fe80::8448:a3ff:fe51:f102]: failure 13 (Permission denied - ipv6: IPv6 >>>> is disabled on this device) >>>> Feb 26 00:24:36 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083476.4885] platform-linux: do-add-ip6-address[2: >>>> 2620:52:9:160c:8448:a3ff:fe51:f102]: failure 13 (Permission denied - >>>> ipv6: IPv6 is disabled on this device) >>>> Feb 26 00:24:36 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083476.4938] l3cfg[0f1985ec14299e62,ifindex=2]: unable to >>>> configure IPv6 route: type unicast fe80::/64 dev 2 metric 1024 mss 0 >>>> rt-src ipv6ll >>>> Feb 26 00:24:38 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083478.4938] ipv6ll[95ab7f3fdbfe643d,ifindex=2]: changed: no IPv6 >>>> link local address to retry after Duplicate Address Detection failures >>>> (back off) >>>> Feb 26 00:24:38 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083478.4943] platform-linux: do-add-ip6-address[2: >>>> 2620:52:9:160c:8448:a3ff:fe51:f102]: failure 13 (Permission denied - >>>> ipv6: IPv6 is disabled on this device) >>>> Feb 26 00:24:48 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083488.5034] platform-linux: do-add-ip6-address[2: >>>> fe80::8448:a3ff:fe51:f102]: failure 13 (Permission denied - ipv6: IPv6 >>>> is disabled on this device) >>>> Feb 26 00:24:48 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083488.5037] platform-linux: do-add-ip6-address[2: >>>> 2620:52:9:160c:8448:a3ff:fe51:f102]: failure 13 (Permission denied - >>>> ipv6: IPv6 is disabled on this device) >>>> Feb 26 00:24:48 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083488.5041] l3cfg[0f1985ec14299e62,ifindex=2]: unable to >>>> configure IPv6 route: type unicast fe80::/64 dev 2 metric 1024 mss 0 >>>> rt-src ipv6ll >>>> Feb 26 00:24:50 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083490.5034] ipv6ll[95ab7f3fdbfe643d,ifindex=2]: changed: no IPv6 >>>> link local address to retry after Duplicate Address Detection failures >>>> (back off) >>>> Feb 26 00:24:50 ibm-p9z-27-lp26 NetworkManager[818]: >>>> [1772083490.5039] platform-linux: do-add-ip6-address[2: >>>> 2620:52:9:160c:8448:a3ff:fe51:f102]: failure 13 (Permission denied - >>>> ipv6: IPv6 is disabled on this device) >>>> Feb 26 00:24:58 ibm-p9z-27-lp26 kernel: Kernel attempted to read user >>>> page (7fff81210000) - exploit attempt? (uid: 0) >>>> Feb 26 00:24:58 ibm-p9z-27-lp26 kernel: ------------[ cut here ]------------ >>>> Feb 26 00:24:58 ibm-p9z-27-lp26 kernel: Bug: Read fault blocked by KUAP! >>>> Feb 26 00:24:58 ibm-p9z-27-lp26 kernel: WARNING: >>>> arch/powerpc/mm/fault.c:231 at bad_kernel_fault.isra.0+0xc8/0x2c0, >>>> CPU#5: lt-ublk.null/57924 >> >> oops, it shouldn't be related with `ublk: report BLK_SPLIT_INTERVAL_CAPABLE`, >> Perhaps one issue lies in the ppcle64 architecture code. > > Agreed, the "Kernel attempted to read user page" error seems > incorrect. The call trace shows this is in copy_from_iter(), so > reading a user page is expected. I too would be suspicious of the > powerpc copy_from_iter() implementation. Looks similar to: https://lore.kernel.org/all/20260109064917.777587-2-sshegde@linux.ibm.com/ That fix was rejected, more acceptable fix here: https://lore.kernel.org/all/20260217124457.89219-1-sayalip@linux.ibm.com/ Let us know if it fixes the issue for you. Christophe