From 2bf380f091eab30441acc699e2d4a15c94aac986 Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Wed, 13 Jan 2016 10:41:24 -0800 Subject: [PATCH] Increase default user space stack size Under RHEL6/CentOS6 the default stack size must be increased to 32K to prevent overflowing the stack when running ztest. This isn't an issue for other distributions due to either the version of pthreads or perhaps the compiler. Doubling the stack size resolves the issue safely for all distribution and leaves us some headroom. $ sudo -E ztest -V -T 300 -f /var/tmp/ 5 vdevs, 7 datasets, 23 threads, 300 seconds... loading space map for vdev 0 of 1, metaslab 0 of 30 ... ... loading space map for vdev 0 of 1, metaslab 14 of 30 ... child died with signal 11 Exited ztest with error 3 Signed-off-by: Brian Behlendorf Closes #4215 --- include/sys/zfs_context.h | 2 +- man/man1/ztest.1 | 7 +++---- module/zfs/txg.c | 2 +- 3 files changed, 5 insertions(+), 6 deletions(-) diff --git a/include/sys/zfs_context.h b/include/sys/zfs_context.h index bd510ab6c71b..2e96aeecda75 100644 --- a/include/sys/zfs_context.h +++ b/include/sys/zfs_context.h @@ -212,7 +212,7 @@ extern int aok; */ #define TS_MAGIC 0x72f158ab4261e538ull #define TS_RUN 0x00000002 -#define TS_STACK_MIN PTHREAD_STACK_MIN +#define TS_STACK_MIN MAX(PTHREAD_STACK_MIN, 32768) #define TS_STACK_MAX (256 * 1024) /* in libzpool, p0 exists only to have its address taken */ diff --git a/man/man1/ztest.1 b/man/man1/ztest.1 index f798bcfcb8e8..ebfacd46dcb0 100644 --- a/man/man1/ztest.1 +++ b/man/man1/ztest.1 @@ -149,11 +149,10 @@ ztest -f / -V -T 120 .TP .B "ZFS_STACK_SIZE=stacksize" Limit the default stack size to \fBstacksize\fR bytes for the purpose of -detecting and debugging kernel stack overflows. For x86_64 platforms this -value should be set as follows to simulate these platforms: \fB8192\fR -(Linux), \fB20480\fR (Illumos), \fB16384\fR (FreeBSD). +detecting and debugging kernel stack overflows. This value defaults to +\fB32K\fR which is double the default \fB16K\fR Linux kernel stack size. -In practice you may need to set these value slightly higher because +In practice, setting the stack size slightly higher is needed because differences in stack usage between kernel and user space can lead to spurious stack overflows (especially when debugging is enabled). The specified value will be rounded up to a floor of PTHREAD_STACK_MIN which is the minimum stack diff --git a/module/zfs/txg.c b/module/zfs/txg.c index d5dff58abb77..ed8007e05238 100644 --- a/module/zfs/txg.c +++ b/module/zfs/txg.c @@ -212,7 +212,7 @@ txg_sync_start(dsl_pool_t *dp) * 32-bit x86. This is due in part to nested pools and * scrub_visitbp() recursion. */ - tx->tx_sync_thread = thread_create(NULL, 32<<10, txg_sync_thread, + tx->tx_sync_thread = thread_create(NULL, 0, txg_sync_thread, dp, 0, &p0, TS_RUN, defclsyspri); mutex_exit(&tx->tx_sync_lock);