When this happpens, is the process holding a single (or very few) shm file references, or references to many shm files ? I wonder if you end up in a scenario where an application very frequently performs exec(), and therefore sometimes the exec() will happen in the window between the unix socket file descriptor reception and call to fcntl FD_CLOEXEC. Thanks, Mathieu ----- On Mar 8, 2022, at 8:29 PM, zhenyu.ren wrote: > Thanks a lot for reply. I do not reply it in bug tracker since I have not gotten > a reliable way to reproduce the leak case. >> ------------------------------------------------------------------ >> 发件人：Mathieu Desnoyers >> 发送时间：2022年3月8日(星期二) 23:26 >> 收件人：zhenyu.ren >> 抄 送：Jonathan Rajotte ; lttng-dev >> >> 主 题：Re: [lttng-dev] 回复： 回复： 回复： shm leak in traced application? >> ----- On Mar 8, 2022, at 12:18 AM, lttng-dev lttng-dev@lists.lttng.org wrote: >> > Hi, >> > In shm_object_table_append_shm()/alloc_shm()， why not calling FD_CLOEXEC fcntl() >> > to shmfds? I guess this omission leads to shm fds leak. >> Those file descriptors are created when received by ustcomm_recv_fds_unix_sock, >> and >> immediately after creation they are set as FD_CLOEXEC. >> We should continue this discussion in the bug tracker as suggested by Jonathan. >> It would greatly help if you can provide a small reproducer. >> Thanks, >> Mathieu >> > Thanks >> > zhenyu.ren >> >> ------------------------------------------------------------------ >> >> 发件人：Jonathan Rajotte-Julien >> >> 发送时间：2022年2月25日(星期五) 22:31 >> >> 收件人：zhenyu.ren >> >> 抄 送：lttng-dev >> >> 主 题：Re: [lttng-dev] 回复： 回复： shm leak in traced application? >> >> Hi zhenyu.ren, >> >> Please open a bug on our bug tracker and provide a reproducer against the latest >> >> stable version (2.13.x). >> >> https://bugs.lttng.org/ >> >> Please follow the guidelines: https://bugs.lttng.org/#Bug-reporting-guidelines >> >> Cheers >> >> On Fri, Feb 25, 2022 at 12:47:34PM +0800, zhenyu.ren via lttng-dev wrote: >> >> > Hi, lttng-dev team >> >>> When lttng-sessiond exits, the ust applications should call >> >>> lttng_ust_objd_table_owner_cleanup() and clean up all shm resource(unmap and >> >>> close). Howerver I do find that the ust applications keep opening "all" of the >> >> > shm fds("/dev/shm/ust-shm-consumer-81132 (deleted)") and do NOT free shm. >> >>> If we run lttng-sessiond again, ust applications can get a new piece of shm and >> >>> a new list of shm fds so double shm usages. Then if we kill lttng-sessiond, >> >>> what the mostlikely happened is ust applications close the new list of shm fds >> >>> and free new shm resource but keeping old shm still. In other word, we can not >> >> > free this piece of shm unless we killing ust applications!!! >> >>> So Is there any possilbe that ust applications failed calling >> >>> lttng_ust_objd_table_owner_cleanup()? Do you have ever see this problem? Do you >> >>> have any advice to free the shm without killling ust applications(I tried to >> >> > dig into kernel shm_open and /dev/shm, but not found any ideas)? >> >> > Thanks in advance >> >> > zhenyu.ren >> >> > ------------------------------------------------------------------ >> >> > 发件人：zhenyu.ren via lttng-dev >> >> > 发送时间：2022年2月23日(星期三) 23:09 >> >> > 收件人：lttng-dev >> >> > 主 题：[lttng-dev] 回复： shm leak in traced application? >> >>> >"I found these items also exist in a traced application which is a long-time >> >> > >running daemon" >> >> > Even if lttng-sessiond has been killed!! >> >> > Thanks >> >> > zhenyu.ren >> >> > ------------------------------------------------------------------ >> >> > 发件人：zhenyu.ren via lttng-dev >> >> > 发送时间：2022年2月23日(星期三) 22:44 >> >> > 收件人：lttng-dev >> >> > 主 题：[lttng-dev] shm leak in traced application? >> >> > Hi, >> >>> There are many items such as "/dev/shm/ust-shm-consumer-81132 (deleted)" exist >> >>> in lttng-sessiond fd spaces. I know it is the result of shm_open() and >> >> > shm_unlnik() in create_posix_shm(). >> >>> However, today, I found these items also exist in a traced application which is >> >>> a long-time running daemon. The most important thing I found is that there >> >> > seems no reliable way to release share memory. >> >>> I tried to kill lttng-sessiond but not always release share memory. Sometimes I >> >>> need to kill the traced application to free share memory....But it is not a >> >> > good idea to kill these applications. >> >> > My questions are: >> >>> 1. Is there any way to release share memory without killing any traced >> >> > application? >> >>> 2. Is it normal that many items such as "/dev/shm/ust-shm-consumer-81132 >> >> > (deleted)" exist in the traced application? >> >> > Thanks >> >> > zhenyu.ren >> >> > _______________________________________________ >> >> > lttng-dev mailing list >> >> > lttng-dev@lists.lttng.org >> >> > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev >> >> -- >> >> Jonathan Rajotte-Julien >> >> EfficiOS >> > _______________________________________________ >> > lttng-dev mailing list >> > lttng-dev@lists.lttng.org >> > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev >> -- >> Mathieu Desnoyers >> EfficiOS Inc. >> http://www.efficios.com -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com