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SubjectRe: [PATCH v7 0/5] kasan: support backing vmalloc space with real shadow memory
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Hi Daniel,

Are any other patches required prior to this series ? I have tried to
apply it on later powerpc/merge branch without success:


[root@localhost linux-powerpc]# git am
/root/Downloads/kasan-support-backing-vmalloc-space-with-real-shadow-memory\(1\).patch

Applying: kasan: support backing vmalloc space with real shadow memory
.git/rebase-apply/patch:389: trailing whitespace.
* (1) (2) (3)
error: patch failed: lib/Kconfig.kasan:142
error: lib/Kconfig.kasan: patch does not apply
Patch failed at 0001 kasan: support backing vmalloc space with real
shadow memory
The copy of the patch that failed is found in: .git/rebase-apply/patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".


[root@localhost linux-powerpc]# git am -3
/root/Downloads/kasan-support-backing-vmalloc-space-with-real-shadow-memory\(1\).patch

Applying: kasan: support backing vmalloc space with real shadow memory
error: sha1 information is lacking or useless (include/linux/vmalloc.h).
error: could not build fake ancestor
Patch failed at 0001 kasan: support backing vmalloc space with real
shadow memory
The copy of the patch that failed is found in: .git/rebase-apply/patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".


Christophe

On 09/03/2019 02:55 PM, Daniel Axtens wrote:
> Currently, vmalloc space is backed by the early shadow page. This
> means that kasan is incompatible with VMAP_STACK.
>
> This series provides a mechanism to back vmalloc space with real,
> dynamically allocated memory. I have only wired up x86, because that's
> the only currently supported arch I can work with easily, but it's
> very easy to wire up other architectures, and it appears that there is
> some work-in-progress code to do this on arm64 and s390.
>
> This has been discussed before in the context of VMAP_STACK:
> - https://bugzilla.kernel.org/show_bug.cgi?id=202009
> - https://lkml.org/lkml/2018/7/22/198
> - https://lkml.org/lkml/2019/7/19/822
>
> In terms of implementation details:
>
> Most mappings in vmalloc space are small, requiring less than a full
> page of shadow space. Allocating a full shadow page per mapping would
> therefore be wasteful. Furthermore, to ensure that different mappings
> use different shadow pages, mappings would have to be aligned to
> KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE.
>
> Instead, share backing space across multiple mappings. Allocate a
> backing page when a mapping in vmalloc space uses a particular page of
> the shadow region. This page can be shared by other vmalloc mappings
> later on.
>
> We hook in to the vmap infrastructure to lazily clean up unused shadow
> memory.
>
>
> v1: https://lore.kernel.org/linux-mm/20190725055503.19507-1-dja@axtens.net/
> v2: https://lore.kernel.org/linux-mm/20190729142108.23343-1-dja@axtens.net/
> Address review comments:
> - Patch 1: use kasan_unpoison_shadow's built-in handling of
> ranges that do not align to a full shadow byte
> - Patch 3: prepopulate pgds rather than faulting things in
> v3: https://lore.kernel.org/linux-mm/20190731071550.31814-1-dja@axtens.net/
> Address comments from Mark Rutland:
> - kasan_populate_vmalloc is a better name
> - handle concurrency correctly
> - various nits and cleanups
> - relax module alignment in KASAN_VMALLOC case
> v4: https://lore.kernel.org/linux-mm/20190815001636.12235-1-dja@axtens.net/
> Changes to patch 1 only:
> - Integrate Mark's rework, thanks Mark!
> - handle the case where kasan_populate_shadow might fail
> - poision shadow on free, allowing the alloc path to just
> unpoision memory that it uses
> v5: https://lore.kernel.org/linux-mm/20190830003821.10737-1-dja@axtens.net/
> Address comments from Christophe Leroy:
> - Fix some issues with my descriptions in commit messages and docs
> - Dynamically free unused shadow pages by hooking into the vmap book-keeping
> - Split out the test into a separate patch
> - Optional patch to track the number of pages allocated
> - minor checkpatch cleanups
> v6: https://lore.kernel.org/linux-mm/20190902112028.23773-1-dja@axtens.net/
> Properly guard freeing pages in patch 1, drop debugging code.
> v7: Add a TLB flush on freeing, thanks Mark Rutland.
> Explain more clearly how I think freeing is concurrency-safe.
>
> Daniel Axtens (5):
> kasan: support backing vmalloc space with real shadow memory
> kasan: add test for vmalloc
> fork: support VMAP_STACK with KASAN_VMALLOC
> x86/kasan: support KASAN_VMALLOC
> kasan debug: track pages allocated for vmalloc shadow
>
> Documentation/dev-tools/kasan.rst | 63 ++++++++
> arch/Kconfig | 9 +-
> arch/x86/Kconfig | 1 +
> arch/x86/mm/kasan_init_64.c | 60 ++++++++
> include/linux/kasan.h | 31 ++++
> include/linux/moduleloader.h | 2 +-
> include/linux/vmalloc.h | 12 ++
> kernel/fork.c | 4 +
> lib/Kconfig.kasan | 16 +++
> lib/test_kasan.c | 26 ++++
> mm/kasan/common.c | 230 ++++++++++++++++++++++++++++++
> mm/kasan/generic_report.c | 3 +
> mm/kasan/kasan.h | 1 +
> mm/vmalloc.c | 45 +++++-
> 14 files changed, 497 insertions(+), 6 deletions(-)
>

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