On 12/18, K.Prasad wrote: > > On Fri, Dec 18, 2009 at 06:27:47PM +0100, Oleg Nesterov wrote: > > On 12/18, Frederic Weisbecker wrote: > > > > > > On Fri, Dec 18, 2009 at 01:56:50AM +0100, Oleg Nesterov wrote: > > > > Hi. > > <snipped> > > > > Single stepping works well for me, after a quick check on > > > gdb. How did you trigger the bug? > > > > Please find the trivial test-case below. It hangs, because > > PTRACE_SINGLESTEP doesn't trigger the trap. > > > > aah...my other mail just criss-crossed yours. > > I quickly ran on the said x86 box, loaded with -tip (commit > 7818b3d0fc68f5c2a85fed86d9fa37131c5a3068) and it runs fine.
Hmm. Just re-tested 2.6.33-rc1 under kvm, it hangs... Oleg. > [r...@llm05 prasadkr]# cat oleg.c > #include <stdio.h> > #include <unistd.h> > #include <signal.h> > #include <sys/ptrace.h> > #include <sys/wait.h> > #include <assert.h> > > int main(void) > { > int pid, status, i; > > pid = fork(); > if (!pid) > for (;;); > > sleep(1); > assert(ptrace(PTRACE_ATTACH, pid, 0,0) == 0); > > assert(pid == wait(&status)); > assert(WIFSTOPPED(status)); > > for (i = 0; i < 10; ++i) { > assert(ptrace(PTRACE_SINGLESTEP, pid, 0,0) == 0); > > printf("wait %d ...\n", i); > assert(pid == wait(&status)); > > assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP); > } > > kill(pid, SIGKILL); > return 0; > } > > [r...@llm05 prasadkr]# gcc -o oleg oleg.c -g -Wall > [r...@llm05 prasadkr]# ./oleg > wait 0 ... > wait 1 ... > wait 2 ... > wait 3 ... > wait 4 ... > wait 5 ... > wait 6 ... > wait 7 ... > wait 8 ... > wait 9 ... > [r...@llm05 prasadkr]# > > Am I missing something here? > > Thanks, > K.Prasad >