path: root/fs/exec.c
diff options
authorRobin Holt <holt@sgi.com>2010-05-11 14:06:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-11 17:33:41 -0700
commit34441427aab4bdb3069a4ffcda69a99357abcb2e (patch)
tree3beebde910f25b0945e9105017fd743c9e5241a5 /fs/exec.c
parent3c904afd7358e9ef515eb5df36b6f25c2b7fc2da (diff)
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 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> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
1 files changed, 0 insertions, 2 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 49cdaa19e5b..e6e94c626c2 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1387,8 +1387,6 @@ 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;