From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47259) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WGlKF-0006aM-Hf for qemu-devel@nongnu.org; Fri, 21 Feb 2014 03:19:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WGlK3-0001tk-4C for qemu-devel@nongnu.org; Fri, 21 Feb 2014 03:19:15 -0500 Received: from e8.ny.us.ibm.com ([32.97.182.138]:51416) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WGlK2-0001tY-VM for qemu-devel@nongnu.org; Fri, 21 Feb 2014 03:19:03 -0500 Received: from /spool/local by e8.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 21 Feb 2014 03:19:02 -0500 From: Michael Roth Date: Fri, 21 Feb 2014 02:17:22 -0600 Message-Id: <1392970647-21528-47-git-send-email-mdroth@linux.vnet.ibm.com> In-Reply-To: <1392970647-21528-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1392970647-21528-1-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 46/51] KVM: Retry KVM_CREATE_VM on EINTR List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: lersek@redhat.com, qemu-stable@nongnu.org, Petar.Jovanovic@imgtec.com From: thomas knych Upstreaming this change from Android (https://android-review.googlesource.com/54211). On heavily loaded machines with many VM instances we see KVM_CREATE_VM failing with EINTR on this path: kvm_dev_ioctl_create_vm -> kvm_create_vm -> kvm_init_mmu_notifier -> mmu_notifier_register -> do_mmu_notifier_register -> mm_take_all_locks which checks if any signals have been raised while it was attaining locks and returns EINTR. Retrying the system call greatly improves reliability. Cc: qemu-stable@nongnu.org Signed-off-by: thomas knych Signed-off-by: Paolo Bonzini (cherry picked from commit 94ccff133820552a859c0fb95e33a539e0b90a75) Signed-off-by: Michael Roth --- kvm-all.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/kvm-all.c b/kvm-all.c index 4478969..951e6e3 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -1431,16 +1431,22 @@ int kvm_init(void) nc++; } - s->vmfd = kvm_ioctl(s, KVM_CREATE_VM, 0); - if (s->vmfd < 0) { + do { + ret = kvm_ioctl(s, KVM_CREATE_VM, 0); + } while (ret == -EINTR); + + if (ret < 0) { + fprintf(stderr, "ioctl(KVM_CREATE_VM) failed: %d %s\n", -s->vmfd, + strerror(-ret)); + #ifdef TARGET_S390X fprintf(stderr, "Please add the 'switch_amode' kernel parameter to " "your host kernel command line\n"); #endif - ret = s->vmfd; goto err; } + s->vmfd = ret; missing_cap = kvm_check_extension_list(s, kvm_required_capabilites); if (!missing_cap) { missing_cap = -- 1.7.9.5