Commit 34441427 authored by Robin Holt's avatar Robin Holt Committed by Linus Torvalds

revert "procfs: provide stack information for threads" and its fixup commits

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 9ebd4eba ("procfs: fix /proc/<pid>/stat stack pointer for kernel
threads") was applied to fix a bug which had kernel threads printing a
userland stack address.

Commit 1306d603 ('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: default avatarRobin Holt <holt@sgi.com>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3c904afd
...@@ -316,7 +316,7 @@ address perms offset dev inode pathname ...@@ -316,7 +316,7 @@ address perms offset dev inode pathname
08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
0804a000-0806b000 rw-p 00000000 00:00 0 [heap] 0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
a7cb1000-a7cb2000 ---p 00000000 00:00 0 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 a7eb2000-a7eb3000 ---p 00000000 00:00 0
a7eb3000-a7ed5000 rw-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 a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
...@@ -352,7 +352,6 @@ is not associated with a file: ...@@ -352,7 +352,6 @@ is not associated with a file:
[stack] = the stack of the main process [stack] = the stack of the main process
[vdso] = the "virtual dynamic shared object", [vdso] = the "virtual dynamic shared object",
the kernel system call handler the kernel system call handler
[threadstack:xxxxxxxx] = the stack of the thread, xxxxxxxx is the stack size
or if empty, the mapping is anonymous. or if empty, the mapping is anonymous.
......
...@@ -1531,8 +1531,6 @@ int compat_do_execve(char * filename, ...@@ -1531,8 +1531,6 @@ int compat_do_execve(char * filename,
if (retval < 0) if (retval < 0)
goto out; goto out;
current->stack_start = current->mm->start_stack;
/* execve succeeded */ /* execve succeeded */
current->fs->in_exec = 0; current->fs->in_exec = 0;
current->in_execve = 0; current->in_execve = 0;
......
...@@ -1387,8 +1387,6 @@ int do_execve(char * filename, ...@@ -1387,8 +1387,6 @@ int do_execve(char * filename,
if (retval < 0) if (retval < 0)
goto out; goto out;
current->stack_start = current->mm->start_stack;
/* execve succeeded */ /* execve succeeded */
current->fs->in_exec = 0; current->fs->in_exec = 0;
current->in_execve = 0; current->in_execve = 0;
......
...@@ -81,7 +81,6 @@ ...@@ -81,7 +81,6 @@
#include <linux/pid_namespace.h> #include <linux/pid_namespace.h>
#include <linux/ptrace.h> #include <linux/ptrace.h>
#include <linux/tracehook.h> #include <linux/tracehook.h>
#include <linux/swapops.h>
#include <asm/pgtable.h> #include <asm/pgtable.h>
#include <asm/processor.h> #include <asm/processor.h>
...@@ -495,7 +494,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, ...@@ -495,7 +494,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
rsslim, rsslim,
mm ? mm->start_code : 0, mm ? mm->start_code : 0,
mm ? mm->end_code : 0, mm ? mm->end_code : 0,
(permitted && mm) ? task->stack_start : 0, (permitted && mm) ? mm->start_stack : 0,
esp, esp,
eip, eip,
/* The signal information here is obsolete. /* The signal information here is obsolete.
......
...@@ -247,25 +247,6 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma) ...@@ -247,25 +247,6 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
} else if (vma->vm_start <= mm->start_stack && } else if (vma->vm_start <= mm->start_stack &&
vma->vm_end >= mm->start_stack) { vma->vm_end >= mm->start_stack) {
name = "[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 { } else {
name = "[vdso]"; name = "[vdso]";
......
...@@ -1497,7 +1497,6 @@ struct task_struct { ...@@ -1497,7 +1497,6 @@ struct task_struct {
/* bitmask of trace recursion */ /* bitmask of trace recursion */
unsigned long trace_recursion; unsigned long trace_recursion;
#endif /* CONFIG_TRACING */ #endif /* CONFIG_TRACING */
unsigned long stack_start;
#ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */ #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */
struct memcg_batch_info { struct memcg_batch_info {
int do_batch; /* incremented when batch uncharge started */ int do_batch; /* incremented when batch uncharge started */
......
...@@ -1114,8 +1114,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, ...@@ -1114,8 +1114,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->bts = NULL; p->bts = NULL;
p->stack_start = stack_start;
/* Perform scheduler related setup. Assign this task to a CPU. */ /* Perform scheduler related setup. Assign this task to a CPU. */
sched_fork(p, clone_flags); sched_fork(p, clone_flags);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment