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[Xen-devel] [PATCH] xenstore: increase default thread stack size to 32k

On several Skylake machines I've observed xl segfaults when running
create or destroy subcommands. Other subcommands may segfault too,
but I've only looked at create and destroy which share a similar

Thread 2 (Thread 0x7ffff7ff3700 (LWP 2941)):
    at /usr/include/bits/unistd.h:44
    at xs.c:398
    fd=<optimized out>) at xs.c:1231

Thread 1 has canceled Thread 2 and is waiting for it in pthread_join().

The backtrace smelled of memory/stack overflow, which was verified by
increasing DEFAULT_THREAD_STACKSIZE to 32kb. Presumably the stack
overflow is observed on Skylake due to a broader CPU feature set which
must be saved within _dl_runtime_resolve and friends.

While PTHREAD_STACK_MIN should advertise a suitable stack size based on
the underlying system, increasing the default size makes xenstore a bit
more robust on systems with insufficient/broken minimums.

Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
 tools/xenstore/xs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/xenstore/xs.c b/tools/xenstore/xs.c
index abffd9cd80..3891e4907c 100644
--- a/tools/xenstore/xs.c
+++ b/tools/xenstore/xs.c
@@ -800,7 +800,7 @@ bool xs_watch(struct xs_handle *h, const char *path, const 
char *token)
        struct iovec iov[2];
-#define DEFAULT_THREAD_STACKSIZE (16 * 1024)
+#define DEFAULT_THREAD_STACKSIZE (32 * 1024)
 #define READ_THREAD_STACKSIZE                                  \

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