On Thu, Mar 23, 2017 at 09:17:14AM +0000, Shichangkuo wrote: > Hi, all > > I used multipath-toosl 0.6.4 for some testing. When executing udevadm > trigger command, I find something wrong with multipathd. Logs are as > follows: > > Mar 15 19:26:00 server155 multipathd: sdj: path wwid changed from > '360002ac000000000000000e700013071' to > '360002ac0000000000000002600013071'. disallowing > > Mar 15 19:26:00 server155 kernel: [706183.837704] multipathd[1165440]: > segfault at 198 ip 0000555f6d022607 sp 00007f1f992f5960 error 4 in > multipathd[555f6d018000+18000] > > > > After parsing the address with objdump, I think uev_update_path > accessing null pointer pp->mpp . Call trace maybe: > > uev_trigger > > uev_update_path > > dm_fail_path(pp->mpp->alias, pp->dev_t); > > > > Has anyone ever met it and how to fix it? Well, if the wwid changes on a path that currently isn't part of a multipath device, this would certainly happen. The issue is simply that we dereference that pointer without checking that it's not NULL first. Now the question is, what to we do if the path changes wwid, but it's not part of a multipath device yet. We could simply print a warning message that the wwid has changed, and allow it to happen, since there's no multipath device currently using the LUN. However, I have seen cases where multiple LUNs that have already been discovered by a node get unmapped, and all the unmapped LUNs from a device get the same ID_SERIAL value in the uevent for the mapping change. This would cause find_multipaths to create a multipath device that includes all of these unmapped devices, which is clearly wrong. So, the best answer is probably to block the change, and simply not call dm_fail_path if pp->mpp == NULL. I can write a patch for this. -Ben > > Thanks! > > Changkuo > > ------------------------------------------------------------------------------------------------------------------------------------- > 本邮件及其附件含有杭州华三通信技术有限公司的保密信息，仅限于发送给上面地址 > 中列出 > 的个人或群组。禁止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、 > 复制、 > 或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并 > 删除本 > 邮件！ > This e-mail and its attachments contain confidential information from H3C, > which is > intended only for the person or entity whose address is listed above. Any > use of the > information contained herein in any way (including, but not limited to, > total or partial > disclosure, reproduction, or dissemination) by persons other than the > intended > recipient(s) is prohibited. If you receive this e-mail in error, please > notify the sender > by phone or email immediately and delete it! > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
