From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759215Ab0EXXLi (ORCPT ); Mon, 24 May 2010 19:11:38 -0400 Received: from kroah.org ([198.145.64.141]:36502 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759039Ab0EXXJf (ORCPT ); Mon, 24 May 2010 19:09:35 -0400 X-Mailbox-Line: From gregkh@clark.site Mon May 24 16:03:51 2010 Message-Id: <20100524230351.574939849@clark.site> User-Agent: quilt/0.48-8.10 Date: Mon, 24 May 2010 15:59:57 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Robin Holt , Stefani Seibold , KOSAKI Motohiro , Michal Simek , Ingo Molnar Subject: [25/34] revert "procfs: provide stack information for threads" and its fixup commits In-Reply-To: <20100524230418.GA12770@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.34-stable review patch. If anyone has any objections, please let us know. ------------------ From: Robin Holt commit 34441427aab4bdb3069a4ffcda69a99357abcb2e upstream. Originally, commit d899bf7b ("procfs: provide stack information for threads") attempted to introduce a new feature for showing where the threadstack was located and how many pages are being utilized by the stack. Commit c44972f1 ("procfs: disable per-task stack usage on NOMMU") was applied to fix the NO_MMU case. Commit 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on 64-bit") was applied to fix a bug in ia32 executables being loaded. Commit 9ebd4eba7 ("procfs: fix /proc//stat stack pointer for kernel threads") was applied to fix a bug which had kernel threads printing a userland stack address. Commit 1306d603f ('proc: partially revert "procfs: provide stack information for threads"') was then applied to revert the stack pages being used to solve a significant performance regression. This patch nearly undoes the effect of all these patches. The reason for reverting these is it provides an unusable value in field 28. For x86_64, a fork will result in the task->stack_start value being updated to the current user top of stack and not the stack start address. This unpredictability of the stack_start value makes it worthless. That includes the intended use of showing how much stack space a thread has. Other architectures will get different values. As an example, ia64 gets 0. The do_fork() and copy_process() functions appear to treat the stack_start and stack_size parameters as architecture specific. I only partially reverted c44972f1 ("procfs: disable per-task stack usage on NOMMU") . If I had completely reverted it, I would have had to change mm/Makefile only build pagewalk.o when CONFIG_PROC_PAGE_MONITOR is configured. Since I could not test the builds without significant effort, I decided to not change mm/Makefile. I only partially reverted 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on 64-bit") . I left the KSTK_ESP() change in place as that seemed worthwhile. Signed-off-by: Robin Holt Cc: Stefani Seibold Cc: KOSAKI Motohiro Cc: Michal Simek Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- Documentation/filesystems/proc.txt | 3 +-- fs/compat.c | 2 -- fs/exec.c | 2 -- fs/proc/array.c | 3 +-- fs/proc/task_mmu.c | 19 ------------------- include/linux/sched.h | 1 - kernel/fork.c | 2 -- 7 files changed, 2 insertions(+), 30 deletions(-) --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -307,7 +307,7 @@ address perms offset dev in 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test 0804a000-0806b000 rw-p 00000000 00:00 0 [heap] a7cb1000-a7cb2000 ---p 00000000 00:00 0 -a7cb2000-a7eb2000 rw-p 00000000 00:00 0 [threadstack:001ff4b4] +a7cb2000-a7eb2000 rw-p 00000000 00:00 0 a7eb2000-a7eb3000 ---p 00000000 00:00 0 a7eb3000-a7ed5000 rw-p 00000000 00:00 0 a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 @@ -343,7 +343,6 @@ is not associated with a file: [stack] = the stack of the main process [vdso] = the "virtual dynamic shared object", the kernel system call handler - [threadstack:xxxxxxxx] = the stack of the thread, xxxxxxxx is the stack size or if empty, the mapping is anonymous. --- a/fs/compat.c +++ b/fs/compat.c @@ -1532,8 +1532,6 @@ int compat_do_execve(char * filename, if (retval < 0) goto out; - current->stack_start = current->mm->start_stack; - /* execve succeeded */ current->fs->in_exec = 0; current->in_execve = 0; --- a/fs/exec.c +++ b/fs/exec.c @@ -1379,8 +1379,6 @@ int do_execve(char * filename, if (retval < 0) goto out; - current->stack_start = current->mm->start_stack; - /* execve succeeded */ current->fs->in_exec = 0; current->in_execve = 0; --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -82,7 +82,6 @@ #include #include #include -#include #include #include @@ -482,7 +481,7 @@ static int do_task_stat(struct seq_file rsslim, mm ? mm->start_code : 0, mm ? mm->end_code : 0, - (permitted && mm) ? task->stack_start : 0, + (permitted && mm) ? mm->start_stack : 0, esp, eip, /* The signal information here is obsolete. --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -243,25 +243,6 @@ static void show_map_vma(struct seq_file } else if (vma->vm_start <= mm->start_stack && vma->vm_end >= mm->start_stack) { name = "[stack]"; - } else { - unsigned long stack_start; - struct proc_maps_private *pmp; - - pmp = m->private; - stack_start = pmp->task->stack_start; - - if (vma->vm_start <= stack_start && - vma->vm_end >= stack_start) { - pad_len_spaces(m, len); - seq_printf(m, - "[threadstack:%08lx]", -#ifdef CONFIG_STACK_GROWSUP - vma->vm_end - stack_start -#else - stack_start - vma->vm_start -#endif - ); - } } } else { name = "[vdso]"; --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1541,7 +1541,6 @@ struct task_struct { /* bitmask of trace recursion */ unsigned long trace_recursion; #endif /* CONFIG_TRACING */ - unsigned long stack_start; }; /* Future-safe accessor for struct task_struct's cpus_allowed. */ --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1123,8 +1123,6 @@ static struct task_struct *copy_process( p->bts = NULL; - p->stack_start = stack_start; - /* Perform scheduler related setup. Assign this task to a CPU. */ sched_fork(p, clone_flags);