Mongos crashed.
Log extact :

• • • glibc detected *** /usr/bin/mongos: free(): corrupted unsorted chunks: 0x0000000018ad2220 ***
      Received signal 11
      Backtrace: *** glibc detected *** /usr/bin/mongos: free(): corrupted unsorted chunks: 0x0000000018ad4520 ***
      Logstream::get called in uninitialized state
      Thu Jun 21 10:32:17 [conn264410] Assertion failure ! inShutdown() client/connpool.cpp 136
    • glibc detected *** /usr/bin/mongos: free(): corrupted unsorted chunks: 0x0000000018ab03f0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aaf7d0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: free(): corrupted unsorted chunks: 0x0000000018e6f540 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***
    • glibc detected *** /usr/bin/mongos: double free or corruption (fasttop): 0x0000000018aafab0 ***

As seen on mms, mongos process used a lot of virtual memory (18Gb) before failure.