FAILED: patch "[PATCH] mm/page_ext.c: check if page_ext is not prepared" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] mm/page_ext.c: check if page_ext is not prepared" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From e492080e640c2d1235ddf3441cae634cfffef7e1 Mon Sep 17 00:00:00 2001
From: Jaewon Kim <jaewon31.kim@samsung.com>
Date: Wed, 15 Nov 2017 17:39:07 -0800
Subject: [PATCH] mm/page_ext.c: check if page_ext is not prepared

online_page_ext() and page_ext_init() allocate page_ext for each
section, but they do not allocate if the first PFN is !pfn_present(pfn)
or !pfn_valid(pfn).  Then section->page_ext remains as NULL.
lookup_page_ext checks NULL only if CONFIG_DEBUG_VM is enabled.  For a
valid PFN, __set_page_owner will try to get page_ext through
lookup_page_ext.  Without CONFIG_DEBUG_VM lookup_page_ext will misuse
NULL pointer as value 0.  This incurrs invalid address access.

This is the panic example when PFN 0x100000 is not valid but PFN
0x13FC00 is being used for page_ext.  section->page_ext is NULL,
get_entry returned invalid page_ext address as 0x1DFA000 for a PFN
0x13FC00.

To avoid this panic, CONFIG_DEBUG_VM should be removed so that page_ext
will be checked at all times.

  Unable to handle kernel paging request at virtual address 01dfa014
  ------------[ cut here ]------------
  Kernel BUG at ffffff80082371e0 [verbose debug info unavailable]
  Internal error: Oops: 96000045 [#1] PREEMPT SMP
  Modules linked in:
  PC is at __set_page_owner+0x48/0x78
  LR is at __set_page_owner+0x44/0x78
    __set_page_owner+0x48/0x78
    get_page_from_freelist+0x880/0x8e8
    __alloc_pages_nodemask+0x14c/0xc48
    __do_page_cache_readahead+0xdc/0x264
    filemap_fault+0x2ac/0x550
    ext4_filemap_fault+0x3c/0x58
    __do_fault+0x80/0x120
    handle_mm_fault+0x704/0xbb0
    do_page_fault+0x2e8/0x394
    do_mem_abort+0x88/0x124

Pre-4.7 kernels also need commit f86e4271978b ("mm: check the return
value of lookup_page_ext for all call sites").

Link: http://lkml.kernel.org/r/20171107094131.14621-1-jaewon31.kim@samsung.com
Fixes: eefa864b701d ("mm/page_ext: resurrect struct page extending code for debugging")
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: <stable@vger.kernel.org>	[depends on f86e427197, see above]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_ext.c b/mm/page_ext.c
index 4f0367d472c4..2c16216c29b6 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -125,7 +125,6 @@ struct page_ext *lookup_page_ext(struct page *page)
 	struct page_ext *base;
 
 	base = NODE_DATA(page_to_nid(page))->node_page_ext;
-#if defined(CONFIG_DEBUG_VM)
 	/*
 	 * The sanity checks the page allocator does upon freeing a
 	 * page can reach here before the page_ext arrays are
@@ -134,7 +133,6 @@ struct page_ext *lookup_page_ext(struct page *page)
 	 */
 	if (unlikely(!base))
 		return NULL;
-#endif
 	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
 					MAX_ORDER_NR_PAGES);
 	return get_entry(base, index);
@@ -199,7 +197,6 @@ struct page_ext *lookup_page_ext(struct page *page)
 {
 	unsigned long pfn = page_to_pfn(page);
 	struct mem_section *section = __pfn_to_section(pfn);
-#if defined(CONFIG_DEBUG_VM)
 	/*
 	 * The sanity checks the page allocator does upon freeing a
 	 * page can reach here before the page_ext arrays are
@@ -208,7 +205,6 @@ struct page_ext *lookup_page_ext(struct page *page)
 	 */
 	if (!section->page_ext)
 		return NULL;
-#endif
 	return get_entry(section->page_ext, pfn);
 }
 

FAILED: patch "[PATCH] mm/page_ext.c: check if page_ext is not prepared" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From e492080e640c2d1235ddf3441cae634cfffef7e1 Mon Sep 17 00:00:00 2001
From: Jaewon Kim <jaewon31.kim@samsung.com>
Date: Wed, 15 Nov 2017 17:39:07 -0800
Subject: [PATCH] mm/page_ext.c: check if page_ext is not prepared

online_page_ext() and page_ext_init() allocate page_ext for each
section, but they do not allocate if the first PFN is !pfn_present(pfn)
or !pfn_valid(pfn).  Then section->page_ext remains as NULL.
lookup_page_ext checks NULL only if CONFIG_DEBUG_VM is enabled.  For a
valid PFN, __set_page_owner will try to get page_ext through
lookup_page_ext.  Without CONFIG_DEBUG_VM lookup_page_ext will misuse
NULL pointer as value 0.  This incurrs invalid address access.

This is the panic example when PFN 0x100000 is not valid but PFN
0x13FC00 is being used for page_ext.  section->page_ext is NULL,
get_entry returned invalid page_ext address as 0x1DFA000 for a PFN
0x13FC00.

To avoid this panic, CONFIG_DEBUG_VM should be removed so that page_ext
will be checked at all times.

  Unable to handle kernel paging request at virtual address 01dfa014
  ------------[ cut here ]------------
  Kernel BUG at ffffff80082371e0 [verbose debug info unavailable]
  Internal error: Oops: 96000045 [#1] PREEMPT SMP
  Modules linked in:
  PC is at __set_page_owner+0x48/0x78
  LR is at __set_page_owner+0x44/0x78
    __set_page_owner+0x48/0x78
    get_page_from_freelist+0x880/0x8e8
    __alloc_pages_nodemask+0x14c/0xc48
    __do_page_cache_readahead+0xdc/0x264
    filemap_fault+0x2ac/0x550
    ext4_filemap_fault+0x3c/0x58
    __do_fault+0x80/0x120
    handle_mm_fault+0x704/0xbb0
    do_page_fault+0x2e8/0x394
    do_mem_abort+0x88/0x124

Pre-4.7 kernels also need commit f86e4271978b ("mm: check the return
value of lookup_page_ext for all call sites").

Link: http://lkml.kernel.org/r/20171107094131.14621-1-jaewon31.kim@samsung.com
Fixes: eefa864b701d ("mm/page_ext: resurrect struct page extending code for debugging")
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: <stable@vger.kernel.org>	[depends on f86e427197, see above]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_ext.c b/mm/page_ext.c
index 4f0367d472c4..2c16216c29b6 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -125,7 +125,6 @@ struct page_ext *lookup_page_ext(struct page *page)
 	struct page_ext *base;
 
 	base = NODE_DATA(page_to_nid(page))->node_page_ext;
-#if defined(CONFIG_DEBUG_VM)
 	/*
 	 * The sanity checks the page allocator does upon freeing a
 	 * page can reach here before the page_ext arrays are
@@ -134,7 +133,6 @@ struct page_ext *lookup_page_ext(struct page *page)
 	 */
 	if (unlikely(!base))
 		return NULL;
-#endif
 	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
 					MAX_ORDER_NR_PAGES);
 	return get_entry(base, index);
@@ -199,7 +197,6 @@ struct page_ext *lookup_page_ext(struct page *page)
 {
 	unsigned long pfn = page_to_pfn(page);
 	struct mem_section *section = __pfn_to_section(pfn);
-#if defined(CONFIG_DEBUG_VM)
 	/*
 	 * The sanity checks the page allocator does upon freeing a
 	 * page can reach here before the page_ext arrays are
@@ -208,7 +205,6 @@ struct page_ext *lookup_page_ext(struct page *page)
 	 */
 	if (!section->page_ext)
 		return NULL;
-#endif
 	return get_entry(section->page_ext, pfn);
 }
 

Re: FAILED: patch "[PATCH] mm/page_ext.c: check if page_ext is not prepared" failed to apply to 4.4-stable tree

[Michal Hocko]

Greg,
the patch is clear about its dependecy for pre-4.7 kernels. I do not see
f86e4271978b queued for the stable tree though. Is it just me not seeing
it or your automation doesn't check for such dependencies?

On Wed 22-11-17 09:37:57, Greg KH wrote:
> >From e492080e640c2d1235ddf3441cae634cfffef7e1 Mon Sep 17 00:00:00 2001
> From: Jaewon Kim <jaewon31.kim@samsung.com>
> Date: Wed, 15 Nov 2017 17:39:07 -0800
> Subject: [PATCH] mm/page_ext.c: check if page_ext is not prepared
> 
> online_page_ext() and page_ext_init() allocate page_ext for each
> section, but they do not allocate if the first PFN is !pfn_present(pfn)
> or !pfn_valid(pfn).  Then section->page_ext remains as NULL.
> lookup_page_ext checks NULL only if CONFIG_DEBUG_VM is enabled.  For a
> valid PFN, __set_page_owner will try to get page_ext through
> lookup_page_ext.  Without CONFIG_DEBUG_VM lookup_page_ext will misuse
> NULL pointer as value 0.  This incurrs invalid address access.
> 
> This is the panic example when PFN 0x100000 is not valid but PFN
> 0x13FC00 is being used for page_ext.  section->page_ext is NULL,
> get_entry returned invalid page_ext address as 0x1DFA000 for a PFN
> 0x13FC00.
> 
> To avoid this panic, CONFIG_DEBUG_VM should be removed so that page_ext
> will be checked at all times.
> 
>   Unable to handle kernel paging request at virtual address 01dfa014
>   ------------[ cut here ]------------
>   Kernel BUG at ffffff80082371e0 [verbose debug info unavailable]
>   Internal error: Oops: 96000045 [#1] PREEMPT SMP
>   Modules linked in:
>   PC is at __set_page_owner+0x48/0x78
>   LR is at __set_page_owner+0x44/0x78
>     __set_page_owner+0x48/0x78
>     get_page_from_freelist+0x880/0x8e8
>     __alloc_pages_nodemask+0x14c/0xc48
>     __do_page_cache_readahead+0xdc/0x264
>     filemap_fault+0x2ac/0x550
>     ext4_filemap_fault+0x3c/0x58
>     __do_fault+0x80/0x120
>     handle_mm_fault+0x704/0xbb0
>     do_page_fault+0x2e8/0x394
>     do_mem_abort+0x88/0x124
> 
> Pre-4.7 kernels also need commit f86e4271978b ("mm: check the return
> value of lookup_page_ext for all call sites").
> 
> Link: http://lkml.kernel.org/r/20171107094131.14621-1-jaewon31.kim@samsung.com
> Fixes: eefa864b701d ("mm/page_ext: resurrect struct page extending code for debugging")
> Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Joonsoo Kim <js1304@gmail.com>
> Cc: <stable@vger.kernel.org>	[depends on f86e427197, see above]
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> 
> diff --git a/mm/page_ext.c b/mm/page_ext.c
> index 4f0367d472c4..2c16216c29b6 100644
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -125,7 +125,6 @@ struct page_ext *lookup_page_ext(struct page *page)
>  	struct page_ext *base;
>  
>  	base = NODE_DATA(page_to_nid(page))->node_page_ext;
> -#if defined(CONFIG_DEBUG_VM)
>  	/*
>  	 * The sanity checks the page allocator does upon freeing a
>  	 * page can reach here before the page_ext arrays are
> @@ -134,7 +133,6 @@ struct page_ext *lookup_page_ext(struct page *page)
>  	 */
>  	if (unlikely(!base))
>  		return NULL;
> -#endif
>  	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
>  					MAX_ORDER_NR_PAGES);
>  	return get_entry(base, index);
> @@ -199,7 +197,6 @@ struct page_ext *lookup_page_ext(struct page *page)
>  {
>  	unsigned long pfn = page_to_pfn(page);
>  	struct mem_section *section = __pfn_to_section(pfn);
> -#if defined(CONFIG_DEBUG_VM)
>  	/*
>  	 * The sanity checks the page allocator does upon freeing a
>  	 * page can reach here before the page_ext arrays are
> @@ -208,7 +205,6 @@ struct page_ext *lookup_page_ext(struct page *page)
>  	 */
>  	if (!section->page_ext)
>  		return NULL;
> -#endif
>  	return get_entry(section->page_ext, pfn);
>  }
>  
> 

-- 
Michal Hocko
SUSE Labs

Re: FAILED: patch "[PATCH] mm/page_ext.c: check if page_ext is not prepared" failed to apply to 4.4-stable tree

[Greg KH]

On Wed, Nov 22, 2017 at 10:47:57AM +0100, Michal Hocko wrote:
> Greg,
> the patch is clear about its dependecy for pre-4.7 kernels. I do not see
> f86e4271978b queued for the stable tree though. Is it just me not seeing
> it or your automation doesn't check for such dependencies?

Yes, I tried to apply the dependency, but that too failed, so I gave a
"FAILED" email response for that patch, as well as this one so that
people can help me out :)

thanks,

greg k-h

Re: FAILED: patch "[PATCH] mm/page_ext.c: check if page_ext is not prepared" failed to apply to 4.4-stable tree

[Michal Hocko]

On Wed 22-11-17 10:54:49, Greg KH wrote:
> On Wed, Nov 22, 2017 at 10:47:57AM +0100, Michal Hocko wrote:
> > Greg,
> > the patch is clear about its dependecy for pre-4.7 kernels. I do not see
> > f86e4271978b queued for the stable tree though. Is it just me not seeing
> > it or your automation doesn't check for such dependencies?
> 
> Yes, I tried to apply the dependency, but that too failed, so I gave a
> "FAILED" email response for that patch, as well as this one so that
> people can help me out :)

Ahh, OK, I didn't see that one as it didn't land neither in lkml nor in
my inbox. Anyway, I will send both patches as a reply to your original
email.
-- 
Michal Hocko
SUSE Labs