[Nfs-ganesha-support] Fwd: Ganesha 2.5, crash /segfault while executing nlm4_Unlock

---------- Forwarded message ---------- From: Sachin Punadikar <punadikar.sachin(a)gmail.com&gt; Date: Tue, Jun 26, 2018 at 3:57 PM Subject: Ganesha 2.5, crash /segfault while executing nlm4_Unlock To: nfs-ganesha-devel <nfs-ganesha-devel(a)lists.sourceforge.net&gt; Hi All, Recently a crash was reported by customer for Ganesha 2.5. (gdb) where #0 0x00007f475872900b in pthread_rwlock_wrlock () from /lib64/libpthread.so.0 #1 0x000000000041eac9 in fsal_obj_handle_fini (obj=0x7f4378028028) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL/commonlib.c:192 #2 0x000000000053180f in mdcache_lru_clean (entry=0x7f4378027ff0) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL /Stackable_FSALs/FSAL_MDCACHE/mdcache_lru.c:589 #3 0x0000000000536587 in _mdcache_lru_unref (entry=0x7f4378027ff0, flags=0, func=0x5a9380 <__func__.23209> "cih_remove_checked", line=406) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL /Stackable_FSALs/FSAL_MDCACHE/mdcache_lru.c:1921 #4 0x0000000000543e91 in cih_remove_checked (entry=0x7f4378027ff0) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL /Stackable_FSALs/FSAL_MDCACHE/mdcache_hash.h:406 #5 0x0000000000544b26 in mdc_clean_entry (entry=0x7f4378027ff0) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL /Stackable_FSALs/FSAL_MDCACHE/mdcache_helpers.c:235 #6 0x000000000053181e in mdcache_lru_clean (entry=0x7f4378027ff0) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL /Stackable_FSALs/FSAL_MDCACHE/mdcache_lru.c:592 #7 0x0000000000536587 in _mdcache_lru_unref (entry=0x7f4378027ff0, flags=0, func=0x5a70af <__func__.23112> "mdcache_put", line=190) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL /Stackable_FSALs/FSAL_MDCACHE/mdcache_lru.c:1921 #8 0x0000000000539666 in mdcache_put (entry=0x7f4378027ff0) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL /Stackable_FSALs/FSAL_MDCACHE/mdcache_lru.h:190 #9 0x000000000053f062 in mdcache_put_ref (obj_hdl=0x7f4378028028) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/FSAL /Stackable_FSALs/FSAL_MDCACHE/mdcache_handle.c:1709 #10 0x000000000049bf0f in nlm4_Unlock (args=0x7f4294165830, req=0x7f4294165028, res=0x7f43f001e0e0) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/Prot ocols/NLM/nlm_Unlock.c:128 #11 0x000000000044c719 in nfs_rpc_execute (reqdata=0x7f4294165000) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/Main NFSD/nfs_worker_thread.c:1290 #12 0x000000000044cf23 in worker_run (ctx=0x3c200e0) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/Main NFSD/nfs_worker_thread.c:1562 #13 0x000000000050a3e7 in fridgethr_start_routine (arg=0x3c200e0) at /usr/src/debug/nfs-ganesha-2.5.3-ibm013.00-0.1.1-Source/supp ort/fridgethr.c:550 #14 0x00007f4758725dc5 in start_thread () from /lib64/libpthread.so.0 #15 0x00007f4757de673d in clone () from /lib64/libc.so.6 A closer look at the backtrace indicates that there was cyclic flow of execution as below: nlm4_Unlock -> mdcache_put_ref -> mdcache_put -> _mdcache_lru_unref -> mdcache_lru_clean -> fsal_obj_handle_fini and then mdc_clean_entry -> cih_remove_checked -> (purposely coping next flow on below line) -> _mdcache_lru_unref -> mdcache_lru_clean -> fsal_obj_handle_fini (currently crashing here) Do we see any code issue here ? Any hints on how to RCA this issue ? Thanks in advance. -- with regards, Sachin Punadikar -- with regards, Sachin Punadikar