[merged mm-hotfixes-stable] mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.patch removed from -mm tree

[merged mm-hotfixes-stable] mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/vmalloc: add a safer version of find_vm_area() for debug
has been removed from the -mm tree.  Its filename was
     mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Subject: mm/vmalloc: add a safer version of find_vm_area() for debug
Date: Mon, 4 Sep 2023 18:08:04 +0000

It is unsafe to dump vmalloc area information when trying to do so from
some contexts.  Add a safer trylock version of the same function to do a
best-effort VMA finding and use it from vmalloc_dump_obj().

[applied test robot feedback on unused function fix.]
[applied Uladzislau feedback on locking.]
Link: https://lkml.kernel.org/r/20230904180806.1002832-1-joel@joelfernandes.org
Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory")
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reported-by: Zhen Lei <thunder.leizhen@huaweicloud.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmalloc.c |   26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

--- a/mm/vmalloc.c~mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug
+++ a/mm/vmalloc.c
@@ -4278,14 +4278,32 @@ void pcpu_free_vm_areas(struct vm_struct
 #ifdef CONFIG_PRINTK
 bool vmalloc_dump_obj(void *object)
 {
-	struct vm_struct *vm;
 	void *objp = (void *)PAGE_ALIGN((unsigned long)object);
+	const void *caller;
+	struct vm_struct *vm;
+	struct vmap_area *va;
+	unsigned long addr;
+	unsigned int nr_pages;
+
+	if (!spin_trylock(&vmap_area_lock))
+		return false;
+	va = __find_vmap_area((unsigned long)objp, &vmap_area_root);
+	if (!va) {
+		spin_unlock(&vmap_area_lock);
+		return false;
+	}
 
-	vm = find_vm_area(objp);
-	if (!vm)
+	vm = va->vm;
+	if (!vm) {
+		spin_unlock(&vmap_area_lock);
 		return false;
+	}
+	addr = (unsigned long)vm->addr;
+	caller = vm->caller;
+	nr_pages = vm->nr_pages;
+	spin_unlock(&vmap_area_lock);
 	pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
-		vm->nr_pages, (unsigned long)vm->addr, vm->caller);
+		nr_pages, addr, caller);
 	return true;
 }
 #endif
_

Patches currently in -mm which might be from joel@joelfernandes.org are

Re: [merged mm-hotfixes-stable] mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.patch removed from -mm tree

[Lorenzo Stoakes]

On Wed, 6 Sept 2023 at 16:09, Andrew Morton <akpm@linux-foundation.org> wrote:
>
>
> The quilt patch titled
>      Subject: mm/vmalloc: add a safer version of find_vm_area() for debug
> has been removed from the -mm tree.  Its filename was
>      mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.patch
>
> This patch was dropped because it was merged into the mm-hotfixes-stable branch
> of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Hmm, I had outstanding review on this :/ I guess I will have to send a
follow up patch to address those concerns...


>
> ------------------------------------------------------
> From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
> Subject: mm/vmalloc: add a safer version of find_vm_area() for debug
> Date: Mon, 4 Sep 2023 18:08:04 +0000
>
> It is unsafe to dump vmalloc area information when trying to do so from
> some contexts.  Add a safer trylock version of the same function to do a
> best-effort VMA finding and use it from vmalloc_dump_obj().
>
> [applied test robot feedback on unused function fix.]
> [applied Uladzislau feedback on locking.]
> Link: https://lkml.kernel.org/r/20230904180806.1002832-1-joel@joelfernandes.org
> Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory")
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> Reported-by: Zhen Lei <thunder.leizhen@huaweicloud.com>
> Cc: Paul E. McKenney <paulmck@kernel.org>
> Cc: Zqiang <qiang.zhang1211@gmail.com>
> Cc: <stable@vger.kernel.org>
> Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
>  mm/vmalloc.c |   26 ++++++++++++++++++++++----
>  1 file changed, 22 insertions(+), 4 deletions(-)
>
> --- a/mm/vmalloc.c~mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug
> +++ a/mm/vmalloc.c
> @@ -4278,14 +4278,32 @@ void pcpu_free_vm_areas(struct vm_struct
>  #ifdef CONFIG_PRINTK
>  bool vmalloc_dump_obj(void *object)
>  {
> -       struct vm_struct *vm;
>         void *objp = (void *)PAGE_ALIGN((unsigned long)object);
> +       const void *caller;
> +       struct vm_struct *vm;
> +       struct vmap_area *va;
> +       unsigned long addr;
> +       unsigned int nr_pages;
> +
> +       if (!spin_trylock(&vmap_area_lock))
> +               return false;
> +       va = __find_vmap_area((unsigned long)objp, &vmap_area_root);
> +       if (!va) {
> +               spin_unlock(&vmap_area_lock);
> +               return false;
> +       }
>
> -       vm = find_vm_area(objp);
> -       if (!vm)
> +       vm = va->vm;
> +       if (!vm) {
> +               spin_unlock(&vmap_area_lock);
>                 return false;
> +       }
> +       addr = (unsigned long)vm->addr;
> +       caller = vm->caller;
> +       nr_pages = vm->nr_pages;
> +       spin_unlock(&vmap_area_lock);
>         pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
> -               vm->nr_pages, (unsigned long)vm->addr, vm->caller);
> +               nr_pages, addr, caller);
>         return true;
>  }
>  #endif
> _
>
> Patches currently in -mm which might be from joel@joelfernandes.org are
>
>


--
Lorenzo Stoakes
https://ljs.io

Re: [merged mm-hotfixes-stable] mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.patch removed from -mm tree

[Joel Fernandes]

> On Sep 6, 2023, at 3:14 PM, Lorenzo Stoakes <lstoakes@gmail.com> wrote:
> 
> On Wed, 6 Sept 2023 at 16:09, Andrew Morton <akpm@linux-foundation.org> wrote:
>> 
>> 
>> The quilt patch titled
>>     Subject: mm/vmalloc: add a safer version of find_vm_area() for debug
>> has been removed from the -mm tree.  Its filename was
>>     mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug.patch
>> 
>> This patch was dropped because it was merged into the mm-hotfixes-stable branch
>> of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> 
> Hmm, I had outstanding review on this :/ I guess I will have to send a
> follow up patch to address those concerns...

That works me because we also had some disagreements on some of the suggestions!

Looking forward to your patch and discussing it!

Cheers,

 - Joel


> 
> 
>> 
>> ------------------------------------------------------
>> From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
>> Subject: mm/vmalloc: add a safer version of find_vm_area() for debug
>> Date: Mon, 4 Sep 2023 18:08:04 +0000
>> 
>> It is unsafe to dump vmalloc area information when trying to do so from
>> some contexts.  Add a safer trylock version of the same function to do a
>> best-effort VMA finding and use it from vmalloc_dump_obj().
>> 
>> [applied test robot feedback on unused function fix.]
>> [applied Uladzislau feedback on locking.]
>> Link: https://lkml.kernel.org/r/20230904180806.1002832-1-joel@joelfernandes.org
>> Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory")
>> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
>> Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
>> Reported-by: Zhen Lei <thunder.leizhen@huaweicloud.com>
>> Cc: Paul E. McKenney <paulmck@kernel.org>
>> Cc: Zqiang <qiang.zhang1211@gmail.com>
>> Cc: <stable@vger.kernel.org>
>> Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
>> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>> ---
>> 
>> mm/vmalloc.c |   26 ++++++++++++++++++++++----
>> 1 file changed, 22 insertions(+), 4 deletions(-)
>> 
>> --- a/mm/vmalloc.c~mm-vmalloc-add-a-safer-version-of-find_vm_area-for-debug
>> +++ a/mm/vmalloc.c
>> @@ -4278,14 +4278,32 @@ void pcpu_free_vm_areas(struct vm_struct
>> #ifdef CONFIG_PRINTK
>> bool vmalloc_dump_obj(void *object)
>> {
>> -       struct vm_struct *vm;
>>        void *objp = (void *)PAGE_ALIGN((unsigned long)object);
>> +       const void *caller;
>> +       struct vm_struct *vm;
>> +       struct vmap_area *va;
>> +       unsigned long addr;
>> +       unsigned int nr_pages;
>> +
>> +       if (!spin_trylock(&vmap_area_lock))
>> +               return false;
>> +       va = __find_vmap_area((unsigned long)objp, &vmap_area_root);
>> +       if (!va) {
>> +               spin_unlock(&vmap_area_lock);
>> +               return false;
>> +       }
>> 
>> -       vm = find_vm_area(objp);
>> -       if (!vm)
>> +       vm = va->vm;
>> +       if (!vm) {
>> +               spin_unlock(&vmap_area_lock);
>>                return false;
>> +       }
>> +       addr = (unsigned long)vm->addr;
>> +       caller = vm->caller;
>> +       nr_pages = vm->nr_pages;
>> +       spin_unlock(&vmap_area_lock);
>>        pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
>> -               vm->nr_pages, (unsigned long)vm->addr, vm->caller);
>> +               nr_pages, addr, caller);
>>        return true;
>> }
>> #endif
>> _
>> 
>> Patches currently in -mm which might be from joel@joelfernandes.org are
>> 
>> 
> 
> 
> --
> Lorenzo Stoakes
> https://ljs.io