Messages in this thread | | | Subject | Re: [PATCH 5.15] mm: validate buddy page before using | From | Xianting Tian <> | Date | Mon, 20 Jun 2022 20:18:40 +0800 |
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在 2022/6/20 下午8:06, Greg KH 写道: > On Mon, Jun 20, 2022 at 07:57:05PM +0800, Xianting Tian wrote: >> 在 2022/6/20 下午7:42, Greg KH 写道: >>> On Mon, Jun 20, 2022 at 06:54:44PM +0800, Xianting Tian wrote: >>>> 在 2022/6/20 下午6:17, Greg KH 写道: >>>>> On Fri, Jun 17, 2022 at 12:17:45AM +0800, Xianting Tian wrote: >>>>>> Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.") >>>>>> fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that >>>>>> can be fixed in a similar way too. >>>>>> >>>>>> In unset_migratetype_isolate(), we also need the fix, so move page_is_buddy() >>>>>> from mm/page_alloc.c to mm/internal.h >>>>>> >>>>>> In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi, >>>>>> so it would have pfn_base=512 and mem_map began with 512th PFN when >>>>>> CONFIG_FLATMEM=y. >>>>>> But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or >>>>>> less than the pfn_base value. We need page_is_buddy() to verify the buddy to >>>>>> prevent accessing an invalid buddy. >>>>>> >>>>>> Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks") >>>>>> Cc: stable@vger.kernel.org >>>>>> Reported-by: zjb194813@alibaba-inc.com >>>>>> Reported-by: tianhu.hh@alibaba-inc.com >>>>>> Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com> >>>>>> --- >>>>>> mm/internal.h | 34 ++++++++++++++++++++++++++++++++++ >>>>>> mm/page_alloc.c | 37 +++---------------------------------- >>>>>> mm/page_isolation.c | 3 ++- >>>>>> 3 files changed, 39 insertions(+), 35 deletions(-) >>>>> What is the commit id of this in Linus's tree? >>>> It is also this one, >>>> >>>> commit 787af64d05cd528aac9ad16752d11bb1c6061bb9 >>>> Author: Zi Yan <ziy@nvidia.com> >>>> Date: Wed Mar 30 15:45:43 2022 -0700 >>>> >>>> mm: page_alloc: validate buddy before check its migratetype. >>>> >>>> Whenever a buddy page is found, page_is_buddy() should be called to >>>> check its validity. Add the missing check during pageblock merge check. >>>> >>>> Fixes: 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable >>>> pageblocks with others") >>>> Link: >>>> https://lore.kernel.org/all/20220330154208.71aca532@gandalf.local.home/ >>>> Reported-and-tested-by: Steven Rostedt <rostedt@goodmis.org> >>>> Signed-off-by: Zi Yan <ziy@nvidia.com> >>>> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> >>> This commit looks nothing like what you posted here. >>> >>> Why the vast difference with no explaination as to why these are so >>> different from the other backports you provided here? Also why is the >>> subject lines changed? >> Yes, the changes of 5.15 are not same with others branches, because we need >> additional fix for 5.15, >> >> You can check it in the thread: >> >> https://lore.kernel.org/linux-mm/435B45C3-E6A5-43B2-A5A2-318C748691FC@nvidia.com/ <https://lore.kernel.org/linux-mm/435B45C3-E6A5-43B2-A5A2-318C748691FC@nvidia.com/> >> >> Right. But pfn_valid_within() was removed since 5.15. So your fix is >> required for kernels between 5.15 and 5.17 (inclusive). > What is "your fix" here? > > This change differs a lot from what is in Linus's tree now, so this all > needs to be resend and fixed up as I mention above if we are going to be > able to take this. As-is, it's all not correct so are dropped.
I think, for branches except 5.15, you can just backport Zi Yan's commit 787af64d05cd in Linus tree. I won't send more patches further,
For 5.15, because it need additional fix except commit 787af64d05cd, I will send a new patch as your comments.
Is it ok for you?
> > thanks, > > greg k-h
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