Re: [PATCH] mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one
On Wed, Jan 09, 2019 at 04:51:17PM -0800, Sean Christopherson wrote:
> Manifests as KVM use-after-free WARNINGs and subsequent "BUG: Bad page
> state in process X" errors when reclaiming from a KVM guest due to KVM
> removing the wrong pages from its own mappings.
With your patch, no badness happened so far. Thanks!
> Reported-by: Adam Borowski
> Fixes: ac46d4f3c432 ("mm/mmu_notifier: use structure for
> invalidate_range_start/end calls v2")
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> - mmu_notifier_range_init(, vma->vm_mm, vma->vm_start,
> - min(vma->vm_end, vma->vm_start +
> + mmu_notifier_range_init(, vma->vm_mm, address,
> + min(vma->vm_end, address +
Meow.
--
⢀⣴⠾⠻⢶⣦⠀ Hans 1 was born and raised in Johannesburg, then moved to Boston,
⣾⠁⢠⠒⠀⣿⡁ and has just became a naturalized citizen. Hans 2's grandparents
⢿⡄⠘⠷⠚⠋⠀ came from Melanesia to Düsseldorf, and he hasn't ever been outside
⠈⠳⣄ Germany until yesterday. Which one is an African-American?
Re: [PATCH] mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one
> The conversion to use a structure for mmu_notifier_invalidate_range_*()
> unintentionally changed the usage in try_to_unmap_one() to init the
> 'struct mmu_notifier_range' with vma->vm_start instead of @address,
> i.e. it invalidates the wrong address range. Revert to the correct
> address range.
>
> Manifests as KVM use-after-free WARNINGs and subsequent "BUG: Bad page
> state in process X" errors when reclaiming from a KVM guest due to KVM
> removing the wrong pages from its own mappings.
>
> Reported-by: leozinho29...@hotmail.com
> Reported-by: Mike Galbraith
> Reported-by: Adam Borowski
> Cc: Jérôme Glisse
> Cc: Christian König
> Cc: Jan Kara
> Cc: Matthew Wilcox
> Cc: Ross Zwisler
> Cc: Dan Williams
> Cc: Paolo Bonzini
> Cc: Radim Krčmář
> Cc: Michal Hocko
> Cc: Felix Kuehling
> Cc: Ralph Campbell
> Cc: John Hubbard
> Cc: Andrew Morton
> Cc: Linus Torvalds
> Fixes: ac46d4f3c432 ("mm/mmu_notifier: use structure for
> invalidate_range_start/end calls v2")
> Signed-off-by: Sean Christopherson
> ---
>
> FWIW, I looked through all other calls to mmu_notifier_range_init() in
> the patch and didn't spot any other unintentional functional changes.
>
> mm/rmap.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 68a1a5b869a5..0454ecc29537 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1371,8 +1371,8 @@ static bool try_to_unmap_one(struct page *page, struct
> vm_area_struct *vma,
>* Note that the page can not be free in this function as call of
>* try_to_unmap() must hold a reference on the page.
>*/
> - mmu_notifier_range_init(, vma->vm_mm, vma->vm_start,
> - min(vma->vm_end, vma->vm_start +
> + mmu_notifier_range_init(, vma->vm_mm, address,
> + min(vma->vm_end, address +
> (PAGE_SIZE << compound_order(page;
> if (PageHuge(page)) {
> /*
> --
I was suspecting this patch for some other issue. But could not spot this after
in depth analyzing the changed "invalidate_range_start/end calls".
Its indeed a good catch.
Reviewed-by: Pankaj gupta
> 2.19.2
>
>
Re: [PATCH] mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one
On Wed, Jan 09, 2019 at 04:51:17PM -0800, Sean Christopherson wrote:
> The conversion to use a structure for mmu_notifier_invalidate_range_*()
> unintentionally changed the usage in try_to_unmap_one() to init the
> 'struct mmu_notifier_range' with vma->vm_start instead of @address,
> i.e. it invalidates the wrong address range. Revert to the correct
> address range.
>
> Manifests as KVM use-after-free WARNINGs and subsequent "BUG: Bad page
> state in process X" errors when reclaiming from a KVM guest due to KVM
> removing the wrong pages from its own mappings.
>
> Reported-by: leozinho29...@hotmail.com
> Reported-by: Mike Galbraith
> Reported-by: Adam Borowski
Reviewed-by: Jérôme Glisse
> Cc: Christian König
> Cc: Jan Kara
> Cc: Matthew Wilcox
> Cc: Ross Zwisler
> Cc: Dan Williams
> Cc: Paolo Bonzini
> Cc: Radim Krčmář
> Cc: Michal Hocko
> Cc: Felix Kuehling
> Cc: Ralph Campbell
> Cc: John Hubbard
> Cc: Andrew Morton
> Cc: Linus Torvalds
> Fixes: ac46d4f3c432 ("mm/mmu_notifier: use structure for
> invalidate_range_start/end calls v2")
> Signed-off-by: Sean Christopherson
> ---
>
> FWIW, I looked through all other calls to mmu_notifier_range_init() in
> the patch and didn't spot any other unintentional functional changes.
>
> mm/rmap.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 68a1a5b869a5..0454ecc29537 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1371,8 +1371,8 @@ static bool try_to_unmap_one(struct page *page, struct
> vm_area_struct *vma,
>* Note that the page can not be free in this function as call of
>* try_to_unmap() must hold a reference on the page.
>*/
> - mmu_notifier_range_init(, vma->vm_mm, vma->vm_start,
> - min(vma->vm_end, vma->vm_start +
> + mmu_notifier_range_init(, vma->vm_mm, address,
> + min(vma->vm_end, address +
> (PAGE_SIZE << compound_order(page;
> if (PageHuge(page)) {
> /*
> --
> 2.19.2
>
