| Message ID | 1459354951-22996-1-git-send-email-tim.gardner@canonical.com |
|---|---|
| State | New |
| Headers | show |
On 30.03.2016 18:22, tim.gardner@canonical.com wrote: > From: Johannes Weiner <hannes@cmpxchg.org> > > BugLink: http://bugs.launchpad.net/bugs/1547231 > > Commit b76437579d13 ("procfs: mark thread stack correctly in > proc/<pid>/maps") added [stack:TID] annotation to /proc/<pid>/maps. > > Finding the task of a stack VMA requires walking the entire thread list, > turning this into quadratic behavior: a thousand threads means a > thousand stacks, so the rendering of /proc/<pid>/maps needs to look at a > million combinations. > > The cost is not in proportion to the usefulness as described in the > patch. > > Drop the [stack:TID] annotation to make /proc/<pid>/maps (and > /proc/<pid>/numa_maps) usable again for higher thread counts. > > The [stack] annotation inside /proc/<pid>/task/<tid>/maps is retained, as > identifying the stack VMA there is an O(1) operation. > > Siddesh said: > "The end users needed a way to identify thread stacks programmatically and > there wasn't a way to do that. I'm afraid I no longer remember (or have > access to the resources that would aid my memory since I changed > employers) the details of their requirement. However, I did do this on my > own time because I thought it was an interesting project for me and nobody > really gave any feedback then as to its utility, so as far as I am > concerned you could roll back the main thread maps information since the > information is available in the thread-specific files" > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> > Cc: "Kirill A. Shutemov" <kirill@shutemov.name> > Cc: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com> > Cc: Shaohua Li <shli@fb.com> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > (back ported from commit 65376df582174ffcec9e6471bf5b0dd79ba05e4a) > Signed-off-by: Tim Gardner <tim.gardner@canonical.com> > > Conflicts: > fs/proc/task_nommu.c > --- > Documentation/filesystems/proc.txt | 9 ++---- > fs/proc/task_mmu.c | 66 +++++++++++++------------------------- > fs/proc/task_nommu.c | 51 ++++++++++++----------------- > include/linux/mm.h | 3 +- > mm/util.c | 27 +--------------- > 5 files changed, 49 insertions(+), 107 deletions(-) > > diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt > index a04b51b..50d6c23 100644 > --- a/Documentation/filesystems/proc.txt > +++ b/Documentation/filesystems/proc.txt > @@ -335,7 +335,7 @@ address perms offset dev inode pathname > a7cb1000-a7cb2000 ---p 00000000 00:00 0 > a7cb2000-a7eb2000 rw-p 00000000 00:00 0 > a7eb2000-a7eb3000 ---p 00000000 00:00 0 > -a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack:1001] > +a7eb3000-a7ed5000 rw-p 00000000 00:00 0 > a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 > a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 > a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 > @@ -367,7 +367,6 @@ is not associated with a file: > > [heap] = the heap of the program > [stack] = the stack of the main process > - [stack:1001] = the stack of the thread with tid 1001 > [vdso] = the "virtual dynamic shared object", > the kernel system call handler > > @@ -375,10 +374,8 @@ is not associated with a file: > > The /proc/PID/task/TID/maps is a view of the virtual memory from the viewpoint > of the individual tasks of a process. In this file you will see a mapping marked > -as [stack] if that task sees it as a stack. This is a key difference from the > -content of /proc/PID/maps, where you will see all mappings that are being used > -as stack by all of those tasks. Hence, for the example above, the task-level > -map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this: > +as [stack] if that task sees it as a stack. Hence, for the example above, the > +task-level map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this: > > 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test > 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index 35f8acb..3c61025 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -243,23 +243,29 @@ static int do_maps_open(struct inode *inode, struct file *file, > sizeof(struct proc_maps_private)); > } > > -static pid_t pid_of_stack(struct proc_maps_private *priv, > - struct vm_area_struct *vma, bool is_pid) > +/* > + * Indicate if the VMA is a stack for the given task; for > + * /proc/PID/maps that is the stack of the main task. > + */ > +static int is_stack(struct proc_maps_private *priv, > + struct vm_area_struct *vma, int is_pid) > { > - struct inode *inode = priv->inode; > - struct task_struct *task; > - pid_t ret = 0; > + int stack = 0; > + > + if (is_pid) { > + stack = vma->vm_start <= vma->vm_mm->start_stack && > + vma->vm_end >= vma->vm_mm->start_stack; > + } else { > + struct inode *inode = priv->inode; > + struct task_struct *task; > > - rcu_read_lock(); > - task = pid_task(proc_pid(inode), PIDTYPE_PID); > - if (task) { > - task = task_of_stack(task, vma, is_pid); > + rcu_read_lock(); > + task = pid_task(proc_pid(inode), PIDTYPE_PID); > if (task) > - ret = task_pid_nr_ns(task, inode->i_sb->s_fs_info); > + stack = vma_is_stack_for_task(vma, task); > + rcu_read_unlock(); > } > - rcu_read_unlock(); > - > - return ret; > + return stack; > } > > static void > @@ -322,8 +328,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid) > > name = arch_vma_name(vma); > if (!name) { > - pid_t tid; > - > if (!mm) { > name = "[vdso]"; > goto done; > @@ -335,21 +339,8 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid) > goto done; > } > > - tid = pid_of_stack(priv, vma, is_pid); > - if (tid != 0) { > - /* > - * Thread stack in /proc/PID/task/TID/maps or > - * the main process stack. > - */ > - if (!is_pid || (vma->vm_start <= mm->start_stack && > - vma->vm_end >= mm->start_stack)) { > - name = "[stack]"; > - } else { > - /* Thread stack in /proc/PID/maps */ > - seq_pad(m, ' '); > - seq_printf(m, "[stack:%d]", tid); > - } > - } > + if (is_stack(priv, vma, is_pid)) > + name = "[stack]"; > } > > done: > @@ -1520,19 +1511,8 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid) > seq_path(m, &file->f_path, "\n\t= "); > } else if (vma->vm_start <= mm->brk && vma->vm_end >= mm->start_brk) { > seq_puts(m, " heap"); > - } else { > - pid_t tid = pid_of_stack(proc_priv, vma, is_pid); > - if (tid != 0) { > - /* > - * Thread stack in /proc/PID/task/TID/maps or > - * the main process stack. > - */ > - if (!is_pid || (vma->vm_start <= mm->start_stack && > - vma->vm_end >= mm->start_stack)) > - seq_puts(m, " stack"); > - else > - seq_printf(m, " stack:%d", tid); > - } > + } else if (is_stack(proc_priv, vma, is_pid)) { > + seq_puts(m, " stack"); > } > > if (is_vm_hugetlb_page(vma)) > diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c > index de6cd6e..1dd6a04 100644 > --- a/fs/proc/task_nommu.c > +++ b/fs/proc/task_nommu.c > @@ -123,23 +123,26 @@ unsigned long task_statm(struct mm_struct *mm, > return size; > } > > -static pid_t pid_of_stack(struct proc_maps_private *priv, > - struct vm_area_struct *vma, bool is_pid) > +static int is_stack(struct proc_maps_private *priv, > + struct vm_area_struct *vma, int is_pid) > { > - struct inode *inode = priv->inode; > - struct task_struct *task; > - pid_t ret = 0; > - > - rcu_read_lock(); > - task = pid_task(proc_pid(inode), PIDTYPE_PID); > - if (task) { > - task = task_of_stack(task, vma, is_pid); > + struct mm_struct *mm = vma->vm_mm; > + int stack = 0; > + > + if (is_pid) { > + stack = vma->vm_start <= mm->start_stack && > + vma->vm_end >= mm->start_stack; > + } else { > + struct inode *inode = priv->inode; > + struct task_struct *task; > + > + rcu_read_lock(); > + task = pid_task(proc_pid(inode), PIDTYPE_PID); > if (task) > - ret = task_pid_nr_ns(task, inode->i_sb->s_fs_info); > + stack = vma_is_stack_for_task(vma, task); > + rcu_read_unlock(); > } > - rcu_read_unlock(); > - > - return ret; > + return stack; > } > > /* > @@ -183,22 +186,10 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma, > > if (file) { > seq_pad(m, ' '); > - seq_path(m, &file->f_path, ""); ^ This changes the second argument of seq_path from &file->f_path to file. Is this really intended? > - } else if (mm) { > - pid_t tid = pid_of_stack(priv, vma, is_pid); > - > - if (tid != 0) { > - seq_pad(m, ' '); > - /* > - * Thread stack in /proc/PID/task/TID/maps or > - * the main process stack. > - */ > - if (!is_pid || (vma->vm_start <= mm->start_stack && > - vma->vm_end >= mm->start_stack)) > - seq_printf(m, "[stack]"); > - else > - seq_printf(m, "[stack:%d]", tid); > - } > + seq_file_path(m, file, ""); > + } else if (mm && is_stack(priv, vma, is_pid)) { > + seq_pad(m, ' '); > + seq_printf(m, "[stack]"); > } > > seq_putc(m, '\n'); > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8121a8b..f0513e3 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1308,8 +1308,7 @@ static inline int stack_guard_page_end(struct vm_area_struct *vma, > !vma_growsup(vma->vm_next, addr); > } > > -extern struct task_struct *task_of_stack(struct task_struct *task, > - struct vm_area_struct *vma, bool in_group); > +int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t); > > extern unsigned long move_page_tables(struct vm_area_struct *vma, > unsigned long old_addr, struct vm_area_struct *new_vma, > diff --git a/mm/util.c b/mm/util.c > index fec39d4..e427c6a 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -161,36 +161,11 @@ void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, > } > > /* Check if the vma is being used as a stack by this task */ > -static int vm_is_stack_for_task(struct task_struct *t, > - struct vm_area_struct *vma) > +int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t) > { > return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); > } > > -/* > - * Check if the vma is being used as a stack. > - * If is_group is non-zero, check in the entire thread group or else > - * just check in the current task. Returns the task_struct of the task > - * that the vma is stack for. Must be called under rcu_read_lock(). > - */ > -struct task_struct *task_of_stack(struct task_struct *task, > - struct vm_area_struct *vma, bool in_group) > -{ > - if (vm_is_stack_for_task(task, vma)) > - return task; > - > - if (in_group) { > - struct task_struct *t; > - > - for_each_thread(task, t) { > - if (vm_is_stack_for_task(t, vma)) > - return t; > - } > - } > - > - return NULL; > -} > - > #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) > void arch_pick_mmap_layout(struct mm_struct *mm) > { >
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 04/04/2016 10:02 AM, Stefan Bader wrote: > On 30.03.2016 18:22, tim.gardner@canonical.com wrote: >> From: Johannes Weiner <hannes@cmpxchg.org> >> >> BugLink: http://bugs.launchpad.net/bugs/1547231 >> >> Commit b76437579d13 ("procfs: mark thread stack correctly in >> proc/<pid>/maps") added [stack:TID] annotation to >> /proc/<pid>/maps. >> >> Finding the task of a stack VMA requires walking the entire >> thread list, turning this into quadratic behavior: a thousand >> threads means a thousand stacks, so the rendering of >> /proc/<pid>/maps needs to look at a million combinations. >> >> The cost is not in proportion to the usefulness as described in >> the patch. >> >> Drop the [stack:TID] annotation to make /proc/<pid>/maps (and >> /proc/<pid>/numa_maps) usable again for higher thread counts. >> >> The [stack] annotation inside /proc/<pid>/task/<tid>/maps is >> retained, as identifying the stack VMA there is an O(1) >> operation. >> >> Siddesh said: "The end users needed a way to identify thread >> stacks programmatically and there wasn't a way to do that. I'm >> afraid I no longer remember (or have access to the resources that >> would aid my memory since I changed employers) the details of >> their requirement. However, I did do this on my own time because >> I thought it was an interesting project for me and nobody really >> gave any feedback then as to its utility, so as far as I am >> concerned you could roll back the main thread maps information >> since the information is available in the thread-specific files" >> >> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill >> A. Shutemov" <kirill@shutemov.name> Cc: Siddhesh Poyarekar >> <siddhesh.poyarekar@gmail.com> Cc: Shaohua Li <shli@fb.com> >> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> >> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> >> (back ported from commit >> 65376df582174ffcec9e6471bf5b0dd79ba05e4a) Signed-off-by: Tim >> Gardner <tim.gardner@canonical.com> >> >> Conflicts: fs/proc/task_nommu.c --- >> Documentation/filesystems/proc.txt | 9 ++---- fs/proc/task_mmu.c >> | 66 +++++++++++++------------------------- fs/proc/task_nommu.c >> | 51 ++++++++++++----------------- include/linux/mm.h >> | 3 +- mm/util.c | 27 +--------------- >> 5 files changed, 49 insertions(+), 107 deletions(-) >> >> diff --git a/Documentation/filesystems/proc.txt >> b/Documentation/filesystems/proc.txt index a04b51b..50d6c23 >> 100644 --- a/Documentation/filesystems/proc.txt +++ >> b/Documentation/filesystems/proc.txt @@ -335,7 +335,7 @@ address >> perms offset dev inode pathname a7cb1000-a7cb2000 ---p >> 00000000 00:00 0 a7cb2000-a7eb2000 rw-p 00000000 00:00 0 >> a7eb2000-a7eb3000 ---p 00000000 00:00 0 -a7eb3000-a7ed5000 rw-p >> 00000000 00:00 0 [stack:1001] +a7eb3000-a7ed5000 rw-p >> 00000000 00:00 0 a7ed5000-a8008000 r-xp 00000000 03:00 4222 >> /lib/libc.so.6 a8008000-a800a000 r--p 00133000 03:00 4222 >> /lib/libc.so.6 a800a000-a800b000 rw-p 00135000 03:00 4222 >> /lib/libc.so.6 @@ -367,7 +367,6 @@ is not associated with a >> file: >> >> [heap] = the heap of the program [stack] >> = the stack of the main process - [stack:1001] = the >> stack of the thread with tid 1001 [vdso] = the >> "virtual dynamic shared object", the kernel system call handler >> >> @@ -375,10 +374,8 @@ is not associated with a file: >> >> The /proc/PID/task/TID/maps is a view of the virtual memory from >> the viewpoint of the individual tasks of a process. In this file >> you will see a mapping marked -as [stack] if that task sees it as >> a stack. This is a key difference from the -content of >> /proc/PID/maps, where you will see all mappings that are being >> used -as stack by all of those tasks. Hence, for the example >> above, the task-level -map, i.e. /proc/PID/task/TID/maps for >> thread 1001 will look like this: +as [stack] if that task sees it >> as a stack. Hence, for the example above, the +task-level map, >> i.e. /proc/PID/task/TID/maps for thread 1001 will look like >> this: >> >> 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test >> 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test diff >> --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index >> 35f8acb..3c61025 100644 --- a/fs/proc/task_mmu.c +++ >> b/fs/proc/task_mmu.c @@ -243,23 +243,29 @@ static int >> do_maps_open(struct inode *inode, struct file *file, >> sizeof(struct proc_maps_private)); } >> >> -static pid_t pid_of_stack(struct proc_maps_private *priv, - >> struct vm_area_struct *vma, bool is_pid) +/* + * Indicate if the >> VMA is a stack for the given task; for + * /proc/PID/maps that is >> the stack of the main task. + */ +static int is_stack(struct >> proc_maps_private *priv, + struct vm_area_struct *vma, int >> is_pid) { - struct inode *inode = priv->inode; - struct >> task_struct *task; - pid_t ret = 0; + int stack = 0; + + if >> (is_pid) { + stack = vma->vm_start <= vma->vm_mm->start_stack >> && + vma->vm_end >= vma->vm_mm->start_stack; + } else { + >> struct inode *inode = priv->inode; + struct task_struct *task; >> >> - rcu_read_lock(); - task = pid_task(proc_pid(inode), >> PIDTYPE_PID); - if (task) { - task = task_of_stack(task, vma, >> is_pid); + rcu_read_lock(); + task = pid_task(proc_pid(inode), >> PIDTYPE_PID); if (task) - ret = task_pid_nr_ns(task, >> inode->i_sb->s_fs_info); + stack = vma_is_stack_for_task(vma, >> task); + rcu_read_unlock(); } - rcu_read_unlock(); - - return >> ret; + return stack; } >> >> static void @@ -322,8 +328,6 @@ show_map_vma(struct seq_file *m, >> struct vm_area_struct *vma, int is_pid) >> >> name = arch_vma_name(vma); if (!name) { - pid_t tid; - if (!mm) >> { name = "[vdso]"; goto done; @@ -335,21 +339,8 @@ >> show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int >> is_pid) goto done; } >> >> - tid = pid_of_stack(priv, vma, is_pid); - if (tid != 0) { - >> /* - * Thread stack in /proc/PID/task/TID/maps or - * the >> main process stack. - */ - if (!is_pid || (vma->vm_start <= >> mm->start_stack && - vma->vm_end >= mm->start_stack)) { - >> name = "[stack]"; - } else { - /* Thread stack in >> /proc/PID/maps */ - seq_pad(m, ' '); - seq_printf(m, >> "[stack:%d]", tid); - } - } + if (is_stack(priv, vma, >> is_pid)) + name = "[stack]"; } >> >> done: @@ -1520,19 +1511,8 @@ static int show_numa_map(struct >> seq_file *m, void *v, int is_pid) seq_path(m, &file->f_path, >> "\n\t= "); } else if (vma->vm_start <= mm->brk && vma->vm_end >= >> mm->start_brk) { seq_puts(m, " heap"); - } else { - pid_t tid = >> pid_of_stack(proc_priv, vma, is_pid); - if (tid != 0) { - /* - >> * Thread stack in /proc/PID/task/TID/maps or - * the main >> process stack. - */ - if (!is_pid || (vma->vm_start <= >> mm->start_stack && - vma->vm_end >= mm->start_stack)) - >> seq_puts(m, " stack"); - else - seq_printf(m, " stack:%d", >> tid); - } + } else if (is_stack(proc_priv, vma, is_pid)) { + >> seq_puts(m, " stack"); } >> >> if (is_vm_hugetlb_page(vma)) diff --git a/fs/proc/task_nommu.c >> b/fs/proc/task_nommu.c index de6cd6e..1dd6a04 100644 --- >> a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -123,23 >> +123,26 @@ unsigned long task_statm(struct mm_struct *mm, return >> size; } >> >> -static pid_t pid_of_stack(struct proc_maps_private *priv, - >> struct vm_area_struct *vma, bool is_pid) +static int >> is_stack(struct proc_maps_private *priv, + struct >> vm_area_struct *vma, int is_pid) { - struct inode *inode = >> priv->inode; - struct task_struct *task; - pid_t ret = 0; - - >> rcu_read_lock(); - task = pid_task(proc_pid(inode), >> PIDTYPE_PID); - if (task) { - task = task_of_stack(task, vma, >> is_pid); + struct mm_struct *mm = vma->vm_mm; + int stack = 0; + >> + if (is_pid) { + stack = vma->vm_start <= mm->start_stack && + >> vma->vm_end >= mm->start_stack; + } else { + struct inode *inode >> = priv->inode; + struct task_struct *task; + + >> rcu_read_lock(); + task = pid_task(proc_pid(inode), >> PIDTYPE_PID); if (task) - ret = task_pid_nr_ns(task, >> inode->i_sb->s_fs_info); + stack = vma_is_stack_for_task(vma, >> task); + rcu_read_unlock(); } - rcu_read_unlock(); - - return >> ret; + return stack; } >> >> /* @@ -183,22 +186,10 @@ static int nommu_vma_show(struct >> seq_file *m, struct vm_area_struct *vma, >> >> if (file) { seq_pad(m, ' '); - seq_path(m, &file->f_path, ""); > > ^ This changes the second argument of seq_path from &file->f_path > to file. Is this really intended? > Note that the replacement function 'seq_file_path()" has a different prototype. >> - } else if (mm) { - pid_t tid = pid_of_stack(priv, vma, >> is_pid); - - if (tid != 0) { - seq_pad(m, ' '); - /* - * >> Thread stack in /proc/PID/task/TID/maps or - * the main >> process stack. - */ - if (!is_pid || (vma->vm_start <= >> mm->start_stack && - vma->vm_end >= mm->start_stack)) - >> seq_printf(m, "[stack]"); - else - seq_printf(m, >> "[stack:%d]", tid); - } + seq_file_path(m, file, ""); + } else >> if (mm && is_stack(priv, vma, is_pid)) { + seq_pad(m, ' '); + >> seq_printf(m, "[stack]"); } >> >> seq_putc(m, '\n'); diff --git a/include/linux/mm.h >> b/include/linux/mm.h index 8121a8b..f0513e3 100644 --- >> a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1308,8 +1308,7 >> @@ static inline int stack_guard_page_end(struct vm_area_struct >> *vma, !vma_growsup(vma->vm_next, addr); } >> >> -extern struct task_struct *task_of_stack(struct task_struct >> *task, - struct vm_area_struct *vma, bool in_group); +int >> vma_is_stack_for_task(struct vm_area_struct *vma, struct >> task_struct *t); >> >> extern unsigned long move_page_tables(struct vm_area_struct >> *vma, unsigned long old_addr, struct vm_area_struct *new_vma, >> diff --git a/mm/util.c b/mm/util.c index fec39d4..e427c6a 100644 >> --- a/mm/util.c +++ b/mm/util.c @@ -161,36 +161,11 @@ void >> __vma_link_list(struct mm_struct *mm, struct vm_area_struct >> *vma, } >> >> /* Check if the vma is being used as a stack by this task */ >> -static int vm_is_stack_for_task(struct task_struct *t, - >> struct vm_area_struct *vma) +int vma_is_stack_for_task(struct >> vm_area_struct *vma, struct task_struct *t) { return >> (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); } >> >> -/* - * Check if the vma is being used as a stack. - * If >> is_group is non-zero, check in the entire thread group or else - >> * just check in the current task. Returns the task_struct of the >> task - * that the vma is stack for. Must be called under >> rcu_read_lock(). - */ -struct task_struct *task_of_stack(struct >> task_struct *task, - struct vm_area_struct *vma, bool >> in_group) -{ - if (vm_is_stack_for_task(task, vma)) - return >> task; - - if (in_group) { - struct task_struct *t; - - >> for_each_thread(task, t) { - if (vm_is_stack_for_task(t, vma)) >> - return t; - } - } - - return NULL; -} - #if >> defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) void >> arch_pick_mmap_layout(struct mm_struct *mm) { >> > > > > - -- Tim Gardner tim.gardner@canonical.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCgAGBQJXApDRAAoJED12yEX6FEfKA0AP/0YSVwdyPWB+lC56XjttAPAi yjEvpiQy+ir/NE8wbMgNha8EiIzDzZ3xkwf36jia0i73PCErwxtmww8mYGO8N249 ZTh9FYl6S8rSZLGbZUfBh7O2++AwlduD7H29HN2kqkOSel481qt947eCF5sZrfEZ h1mq01wCUFC/usRgjxDnGadE+kCRdGT4yDlVSyGxz9iNE5IETwZG6fvkdBpuDnBs HC5bnclP+WrQtevT2SmEAfcf5oF2tyhrkZ5HLIw+Oghtm4rwsQNHIjvItzxBfo7P 0o+2Pjj7Ep2BixrX9rCwna1Gr9T0lg16DJr0qBCSPMbZkMmxrUZB/DPA2gjqhWwl 6EerUdFj7fFWX7Q3g56/FYc6se69oDFgbhA40AIArb5MoWTU9qmVe+ev6PnCH1F8 iXj5ff/LOhvykg8XkvAK7ZM+IitMJv94npbRUAqskSdBcCwbeqB6hVsoiQA0zRMI rlQ28/tZjz8/2o+yH2fpmR8/SLTZHexvCJq8p+gDt+FiqYNMrdl2oNCmX4iRRxaR J6o5/gG/haEkv6GB1UAl7ZmpEuZKXVJcpVB9TIcMc6xGu/AEymol/CtQ69ASddNY +xcoddRrPo0YI17TR41kgNZqV0Xc8AWr3pr3ax2RcfXBcuY22jPjmXOc7esgzKoB 91RAPj21AaLl0+EYaNyP =Z/z8 -----END PGP SIGNATURE-----
On 04.04.2016 18:05, Tim Gardner wrote: > On 04/04/2016 10:02 AM, Stefan Bader wrote: >> On 30.03.2016 18:22, tim.gardner@canonical.com wrote: >>> From: Johannes Weiner <hannes@cmpxchg.org> >>> >>> BugLink: http://bugs.launchpad.net/bugs/1547231 >>> >>> Commit b76437579d13 ("procfs: mark thread stack correctly in >>> proc/<pid>/maps") added [stack:TID] annotation to >>> /proc/<pid>/maps. >>> >>> Finding the task of a stack VMA requires walking the entire >>> thread list, turning this into quadratic behavior: a thousand >>> threads means a thousand stacks, so the rendering of >>> /proc/<pid>/maps needs to look at a million combinations. >>> >>> The cost is not in proportion to the usefulness as described in >>> the patch. >>> >>> Drop the [stack:TID] annotation to make /proc/<pid>/maps (and >>> /proc/<pid>/numa_maps) usable again for higher thread counts. >>> >>> The [stack] annotation inside /proc/<pid>/task/<tid>/maps is >>> retained, as identifying the stack VMA there is an O(1) >>> operation. >>> >>> Siddesh said: "The end users needed a way to identify thread >>> stacks programmatically and there wasn't a way to do that. I'm >>> afraid I no longer remember (or have access to the resources that >>> would aid my memory since I changed employers) the details of >>> their requirement. However, I did do this on my own time because >>> I thought it was an interesting project for me and nobody really >>> gave any feedback then as to its utility, so as far as I am >>> concerned you could roll back the main thread maps information >>> since the information is available in the thread-specific files" >>> >>> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill >>> A. Shutemov" <kirill@shutemov.name> Cc: Siddhesh Poyarekar >>> <siddhesh.poyarekar@gmail.com> Cc: Shaohua Li <shli@fb.com> >>> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> >>> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> >>> (back ported from commit >>> 65376df582174ffcec9e6471bf5b0dd79ba05e4a) Signed-off-by: Tim >>> Gardner <tim.gardner@canonical.com> >>> >>> Conflicts: fs/proc/task_nommu.c --- >>> Documentation/filesystems/proc.txt | 9 ++---- fs/proc/task_mmu.c >>> | 66 +++++++++++++------------------------- fs/proc/task_nommu.c >>> | 51 ++++++++++++----------------- include/linux/mm.h >>> | 3 +- mm/util.c | 27 +--------------- >>> 5 files changed, 49 insertions(+), 107 deletions(-) >>> >>> diff --git a/Documentation/filesystems/proc.txt >>> b/Documentation/filesystems/proc.txt index a04b51b..50d6c23 >>> 100644 --- a/Documentation/filesystems/proc.txt +++ >>> b/Documentation/filesystems/proc.txt @@ -335,7 +335,7 @@ address >>> perms offset dev inode pathname a7cb1000-a7cb2000 ---p >>> 00000000 00:00 0 a7cb2000-a7eb2000 rw-p 00000000 00:00 0 >>> a7eb2000-a7eb3000 ---p 00000000 00:00 0 -a7eb3000-a7ed5000 rw-p >>> 00000000 00:00 0 [stack:1001] +a7eb3000-a7ed5000 rw-p >>> 00000000 00:00 0 a7ed5000-a8008000 r-xp 00000000 03:00 4222 >>> /lib/libc.so.6 a8008000-a800a000 r--p 00133000 03:00 4222 >>> /lib/libc.so.6 a800a000-a800b000 rw-p 00135000 03:00 4222 >>> /lib/libc.so.6 @@ -367,7 +367,6 @@ is not associated with a >>> file: >>> >>> [heap] = the heap of the program [stack] >>> = the stack of the main process - [stack:1001] = the >>> stack of the thread with tid 1001 [vdso] = the >>> "virtual dynamic shared object", the kernel system call handler >>> >>> @@ -375,10 +374,8 @@ is not associated with a file: >>> >>> The /proc/PID/task/TID/maps is a view of the virtual memory from >>> the viewpoint of the individual tasks of a process. In this file >>> you will see a mapping marked -as [stack] if that task sees it as >>> a stack. This is a key difference from the -content of >>> /proc/PID/maps, where you will see all mappings that are being >>> used -as stack by all of those tasks. Hence, for the example >>> above, the task-level -map, i.e. /proc/PID/task/TID/maps for >>> thread 1001 will look like this: +as [stack] if that task sees it >>> as a stack. Hence, for the example above, the +task-level map, >>> i.e. /proc/PID/task/TID/maps for thread 1001 will look like >>> this: >>> >>> 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test >>> 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test diff >>> --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index >>> 35f8acb..3c61025 100644 --- a/fs/proc/task_mmu.c +++ >>> b/fs/proc/task_mmu.c @@ -243,23 +243,29 @@ static int >>> do_maps_open(struct inode *inode, struct file *file, >>> sizeof(struct proc_maps_private)); } >>> >>> -static pid_t pid_of_stack(struct proc_maps_private *priv, - >>> struct vm_area_struct *vma, bool is_pid) +/* + * Indicate if the >>> VMA is a stack for the given task; for + * /proc/PID/maps that is >>> the stack of the main task. + */ +static int is_stack(struct >>> proc_maps_private *priv, + struct vm_area_struct *vma, int >>> is_pid) { - struct inode *inode = priv->inode; - struct >>> task_struct *task; - pid_t ret = 0; + int stack = 0; + + if >>> (is_pid) { + stack = vma->vm_start <= vma->vm_mm->start_stack >>> && + vma->vm_end >= vma->vm_mm->start_stack; + } else { + >>> struct inode *inode = priv->inode; + struct task_struct *task; >>> >>> - rcu_read_lock(); - task = pid_task(proc_pid(inode), >>> PIDTYPE_PID); - if (task) { - task = task_of_stack(task, vma, >>> is_pid); + rcu_read_lock(); + task = pid_task(proc_pid(inode), >>> PIDTYPE_PID); if (task) - ret = task_pid_nr_ns(task, >>> inode->i_sb->s_fs_info); + stack = vma_is_stack_for_task(vma, >>> task); + rcu_read_unlock(); } - rcu_read_unlock(); - - return >>> ret; + return stack; } >>> >>> static void @@ -322,8 +328,6 @@ show_map_vma(struct seq_file *m, >>> struct vm_area_struct *vma, int is_pid) >>> >>> name = arch_vma_name(vma); if (!name) { - pid_t tid; - if (!mm) >>> { name = "[vdso]"; goto done; @@ -335,21 +339,8 @@ >>> show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int >>> is_pid) goto done; } >>> >>> - tid = pid_of_stack(priv, vma, is_pid); - if (tid != 0) { - >>> /* - * Thread stack in /proc/PID/task/TID/maps or - * the >>> main process stack. - */ - if (!is_pid || (vma->vm_start <= >>> mm->start_stack && - vma->vm_end >= mm->start_stack)) { - >>> name = "[stack]"; - } else { - /* Thread stack in >>> /proc/PID/maps */ - seq_pad(m, ' '); - seq_printf(m, >>> "[stack:%d]", tid); - } - } + if (is_stack(priv, vma, >>> is_pid)) + name = "[stack]"; } >>> >>> done: @@ -1520,19 +1511,8 @@ static int show_numa_map(struct >>> seq_file *m, void *v, int is_pid) seq_path(m, &file->f_path, >>> "\n\t= "); } else if (vma->vm_start <= mm->brk && vma->vm_end >= >>> mm->start_brk) { seq_puts(m, " heap"); - } else { - pid_t tid = >>> pid_of_stack(proc_priv, vma, is_pid); - if (tid != 0) { - /* - >>> * Thread stack in /proc/PID/task/TID/maps or - * the main >>> process stack. - */ - if (!is_pid || (vma->vm_start <= >>> mm->start_stack && - vma->vm_end >= mm->start_stack)) - >>> seq_puts(m, " stack"); - else - seq_printf(m, " stack:%d", >>> tid); - } + } else if (is_stack(proc_priv, vma, is_pid)) { + >>> seq_puts(m, " stack"); } >>> >>> if (is_vm_hugetlb_page(vma)) diff --git a/fs/proc/task_nommu.c >>> b/fs/proc/task_nommu.c index de6cd6e..1dd6a04 100644 --- >>> a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -123,23 >>> +123,26 @@ unsigned long task_statm(struct mm_struct *mm, return >>> size; } >>> >>> -static pid_t pid_of_stack(struct proc_maps_private *priv, - >>> struct vm_area_struct *vma, bool is_pid) +static int >>> is_stack(struct proc_maps_private *priv, + struct >>> vm_area_struct *vma, int is_pid) { - struct inode *inode = >>> priv->inode; - struct task_struct *task; - pid_t ret = 0; - - >>> rcu_read_lock(); - task = pid_task(proc_pid(inode), >>> PIDTYPE_PID); - if (task) { - task = task_of_stack(task, vma, >>> is_pid); + struct mm_struct *mm = vma->vm_mm; + int stack = 0; + >>> + if (is_pid) { + stack = vma->vm_start <= mm->start_stack && + >>> vma->vm_end >= mm->start_stack; + } else { + struct inode *inode >>> = priv->inode; + struct task_struct *task; + + >>> rcu_read_lock(); + task = pid_task(proc_pid(inode), >>> PIDTYPE_PID); if (task) - ret = task_pid_nr_ns(task, >>> inode->i_sb->s_fs_info); + stack = vma_is_stack_for_task(vma, >>> task); + rcu_read_unlock(); } - rcu_read_unlock(); - - return >>> ret; + return stack; } >>> >>> /* @@ -183,22 +186,10 @@ static int nommu_vma_show(struct >>> seq_file *m, struct vm_area_struct *vma, >>> >>> if (file) { seq_pad(m, ' '); - seq_path(m, &file->f_path, ""); > >> ^ This changes the second argument of seq_path from &file->f_path >> to file. Is this really intended? > > > Note that the replacement function 'seq_file_path()" has a different > prototype. Meh ok, so its probably only confusing and unnecessary. :-P But ok, as long as it compiles... I won't complain further. > >>> - } else if (mm) { - pid_t tid = pid_of_stack(priv, vma, >>> is_pid); - - if (tid != 0) { - seq_pad(m, ' '); - /* - * >>> Thread stack in /proc/PID/task/TID/maps or - * the main >>> process stack. - */ - if (!is_pid || (vma->vm_start <= >>> mm->start_stack && - vma->vm_end >= mm->start_stack)) - >>> seq_printf(m, "[stack]"); - else - seq_printf(m, >>> "[stack:%d]", tid); - } + seq_file_path(m, file, ""); + } else >>> if (mm && is_stack(priv, vma, is_pid)) { + seq_pad(m, ' '); + >>> seq_printf(m, "[stack]"); } >>> >>> seq_putc(m, '\n'); diff --git a/include/linux/mm.h >>> b/include/linux/mm.h index 8121a8b..f0513e3 100644 --- >>> a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1308,8 +1308,7 >>> @@ static inline int stack_guard_page_end(struct vm_area_struct >>> *vma, !vma_growsup(vma->vm_next, addr); } >>> >>> -extern struct task_struct *task_of_stack(struct task_struct >>> *task, - struct vm_area_struct *vma, bool in_group); +int >>> vma_is_stack_for_task(struct vm_area_struct *vma, struct >>> task_struct *t); >>> >>> extern unsigned long move_page_tables(struct vm_area_struct >>> *vma, unsigned long old_addr, struct vm_area_struct *new_vma, >>> diff --git a/mm/util.c b/mm/util.c index fec39d4..e427c6a 100644 >>> --- a/mm/util.c +++ b/mm/util.c @@ -161,36 +161,11 @@ void >>> __vma_link_list(struct mm_struct *mm, struct vm_area_struct >>> *vma, } >>> >>> /* Check if the vma is being used as a stack by this task */ >>> -static int vm_is_stack_for_task(struct task_struct *t, - >>> struct vm_area_struct *vma) +int vma_is_stack_for_task(struct >>> vm_area_struct *vma, struct task_struct *t) { return >>> (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); } >>> >>> -/* - * Check if the vma is being used as a stack. - * If >>> is_group is non-zero, check in the entire thread group or else - >>> * just check in the current task. Returns the task_struct of the >>> task - * that the vma is stack for. Must be called under >>> rcu_read_lock(). - */ -struct task_struct *task_of_stack(struct >>> task_struct *task, - struct vm_area_struct *vma, bool >>> in_group) -{ - if (vm_is_stack_for_task(task, vma)) - return >>> task; - - if (in_group) { - struct task_struct *t; - - >>> for_each_thread(task, t) { - if (vm_is_stack_for_task(t, vma)) >>> - return t; - } - } - - return NULL; -} - #if >>> defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) void >>> arch_pick_mmap_layout(struct mm_struct *mm) { >>> > > > > > > >
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index a04b51b..50d6c23 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -335,7 +335,7 @@ address perms offset dev inode pathname a7cb1000-a7cb2000 ---p 00000000 00:00 0 a7cb2000-a7eb2000 rw-p 00000000 00:00 0 a7eb2000-a7eb3000 ---p 00000000 00:00 0 -a7eb3000-a7ed5000 rw-p 00000000 00:00 0 [stack:1001] +a7eb3000-a7ed5000 rw-p 00000000 00:00 0 a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6 a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6 a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6 @@ -367,7 +367,6 @@ is not associated with a file: [heap] = the heap of the program [stack] = the stack of the main process - [stack:1001] = the stack of the thread with tid 1001 [vdso] = the "virtual dynamic shared object", the kernel system call handler @@ -375,10 +374,8 @@ is not associated with a file: The /proc/PID/task/TID/maps is a view of the virtual memory from the viewpoint of the individual tasks of a process. In this file you will see a mapping marked -as [stack] if that task sees it as a stack. This is a key difference from the -content of /proc/PID/maps, where you will see all mappings that are being used -as stack by all of those tasks. Hence, for the example above, the task-level -map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this: +as [stack] if that task sees it as a stack. Hence, for the example above, the +task-level map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this: 08048000-08049000 r-xp 00000000 03:00 8312 /opt/test 08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 35f8acb..3c61025 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -243,23 +243,29 @@ static int do_maps_open(struct inode *inode, struct file *file, sizeof(struct proc_maps_private)); } -static pid_t pid_of_stack(struct proc_maps_private *priv, - struct vm_area_struct *vma, bool is_pid) +/* + * Indicate if the VMA is a stack for the given task; for + * /proc/PID/maps that is the stack of the main task. + */ +static int is_stack(struct proc_maps_private *priv, + struct vm_area_struct *vma, int is_pid) { - struct inode *inode = priv->inode; - struct task_struct *task; - pid_t ret = 0; + int stack = 0; + + if (is_pid) { + stack = vma->vm_start <= vma->vm_mm->start_stack && + vma->vm_end >= vma->vm_mm->start_stack; + } else { + struct inode *inode = priv->inode; + struct task_struct *task; - rcu_read_lock(); - task = pid_task(proc_pid(inode), PIDTYPE_PID); - if (task) { - task = task_of_stack(task, vma, is_pid); + rcu_read_lock(); + task = pid_task(proc_pid(inode), PIDTYPE_PID); if (task) - ret = task_pid_nr_ns(task, inode->i_sb->s_fs_info); + stack = vma_is_stack_for_task(vma, task); + rcu_read_unlock(); } - rcu_read_unlock(); - - return ret; + return stack; } static void @@ -322,8 +328,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid) name = arch_vma_name(vma); if (!name) { - pid_t tid; - if (!mm) { name = "[vdso]"; goto done; @@ -335,21 +339,8 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid) goto done; } - tid = pid_of_stack(priv, vma, is_pid); - if (tid != 0) { - /* - * Thread stack in /proc/PID/task/TID/maps or - * the main process stack. - */ - if (!is_pid || (vma->vm_start <= mm->start_stack && - vma->vm_end >= mm->start_stack)) { - name = "[stack]"; - } else { - /* Thread stack in /proc/PID/maps */ - seq_pad(m, ' '); - seq_printf(m, "[stack:%d]", tid); - } - } + if (is_stack(priv, vma, is_pid)) + name = "[stack]"; } done: @@ -1520,19 +1511,8 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid) seq_path(m, &file->f_path, "\n\t= "); } else if (vma->vm_start <= mm->brk && vma->vm_end >= mm->start_brk) { seq_puts(m, " heap"); - } else { - pid_t tid = pid_of_stack(proc_priv, vma, is_pid); - if (tid != 0) { - /* - * Thread stack in /proc/PID/task/TID/maps or - * the main process stack. - */ - if (!is_pid || (vma->vm_start <= mm->start_stack && - vma->vm_end >= mm->start_stack)) - seq_puts(m, " stack"); - else - seq_printf(m, " stack:%d", tid); - } + } else if (is_stack(proc_priv, vma, is_pid)) { + seq_puts(m, " stack"); } if (is_vm_hugetlb_page(vma)) diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c index de6cd6e..1dd6a04 100644 --- a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -123,23 +123,26 @@ unsigned long task_statm(struct mm_struct *mm, return size; } -static pid_t pid_of_stack(struct proc_maps_private *priv, - struct vm_area_struct *vma, bool is_pid) +static int is_stack(struct proc_maps_private *priv, + struct vm_area_struct *vma, int is_pid) { - struct inode *inode = priv->inode; - struct task_struct *task; - pid_t ret = 0; - - rcu_read_lock(); - task = pid_task(proc_pid(inode), PIDTYPE_PID); - if (task) { - task = task_of_stack(task, vma, is_pid); + struct mm_struct *mm = vma->vm_mm; + int stack = 0; + + if (is_pid) { + stack = vma->vm_start <= mm->start_stack && + vma->vm_end >= mm->start_stack; + } else { + struct inode *inode = priv->inode; + struct task_struct *task; + + rcu_read_lock(); + task = pid_task(proc_pid(inode), PIDTYPE_PID); if (task) - ret = task_pid_nr_ns(task, inode->i_sb->s_fs_info); + stack = vma_is_stack_for_task(vma, task); + rcu_read_unlock(); } - rcu_read_unlock(); - - return ret; + return stack; } /* @@ -183,22 +186,10 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma, if (file) { seq_pad(m, ' '); - seq_path(m, &file->f_path, ""); - } else if (mm) { - pid_t tid = pid_of_stack(priv, vma, is_pid); - - if (tid != 0) { - seq_pad(m, ' '); - /* - * Thread stack in /proc/PID/task/TID/maps or - * the main process stack. - */ - if (!is_pid || (vma->vm_start <= mm->start_stack && - vma->vm_end >= mm->start_stack)) - seq_printf(m, "[stack]"); - else - seq_printf(m, "[stack:%d]", tid); - } + seq_file_path(m, file, ""); + } else if (mm && is_stack(priv, vma, is_pid)) { + seq_pad(m, ' '); + seq_printf(m, "[stack]"); } seq_putc(m, '\n'); diff --git a/include/linux/mm.h b/include/linux/mm.h index 8121a8b..f0513e3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1308,8 +1308,7 @@ static inline int stack_guard_page_end(struct vm_area_struct *vma, !vma_growsup(vma->vm_next, addr); } -extern struct task_struct *task_of_stack(struct task_struct *task, - struct vm_area_struct *vma, bool in_group); +int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t); extern unsigned long move_page_tables(struct vm_area_struct *vma, unsigned long old_addr, struct vm_area_struct *new_vma, diff --git a/mm/util.c b/mm/util.c index fec39d4..e427c6a 100644 --- a/mm/util.c +++ b/mm/util.c @@ -161,36 +161,11 @@ void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, } /* Check if the vma is being used as a stack by this task */ -static int vm_is_stack_for_task(struct task_struct *t, - struct vm_area_struct *vma) +int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t) { return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); } -/* - * Check if the vma is being used as a stack. - * If is_group is non-zero, check in the entire thread group or else - * just check in the current task. Returns the task_struct of the task - * that the vma is stack for. Must be called under rcu_read_lock(). - */ -struct task_struct *task_of_stack(struct task_struct *task, - struct vm_area_struct *vma, bool in_group) -{ - if (vm_is_stack_for_task(task, vma)) - return task; - - if (in_group) { - struct task_struct *t; - - for_each_thread(task, t) { - if (vm_is_stack_for_task(t, vma)) - return t; - } - } - - return NULL; -} - #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) void arch_pick_mmap_layout(struct mm_struct *mm) {