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authorRobin Holt <holt@sgi.com>2010-05-11 14:06:46 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2010-05-26 14:29:19 -0700
commit92d664daf9de677afcbf392fac48b734d752abff (patch)
treebc96a18e29f3269527c25d6662dabb36e607c1f4 /fs/proc
parentc8c4c2f04ba486355d7bc6d909a0723acd10f91d (diff)
revert "procfs: provide stack information for threads" and its fixup commits
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/<pid>/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 <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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/array.c3
-rw-r--r--fs/proc/task_mmu.c19
2 files changed, 1 insertions, 21 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 240787d2e998..725a650bbbb8 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -82,7 +82,6 @@
#include <linux/pid_namespace.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
-#include <linux/swapops.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
@@ -482,7 +481,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
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.
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2a1bef9203c6..366b1017a4f1 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -243,25 +243,6 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
} 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]";