- 03 Oct, 2022 40 commits
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Andrey Konovalov authored
Add a kasan_print_aux_stacks() helper that prints the auxiliary stack traces for the Generic mode. This change hides references to alloc_meta from the common reporting code. This is desired as only the Generic mode will be using per-object metadata after this series. Link: https://lkml.kernel.org/r/67c7a9ea6615533762b1f8ccc267cd7f9bafb749.1662411799.git.andreyknvl@google.comSigned-off-by:
Andrey Konovalov <andreyknvl@google.com> Reviewed-by:
Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Peter Collingbourne <pcc@google.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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Andrey Konovalov authored
Drop CONFIG_KASAN_TAGS_IDENTIFY and related code to simplify making changes to the reporting code. The dropped functionality will be restored in the following patches in this series. Link: https://lkml.kernel.org/r/4c66ba98eb237e9ed9312c19d423bbcf4ecf88f8.1662411799.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Provide standalone implementations of save_alloc_info() for the Generic and tag-based modes. For now, the implementations are the same, but they will diverge later in the series. Link: https://lkml.kernel.org/r/77f1a078489c1e859aedb5403f772e5e1f7410a0.1662411799.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Move kasan_info.is_kmalloc check out of save_alloc_info(). This is a preparatory change that simplifies the following patches in this series. Link: https://lkml.kernel.org/r/df89f1915b788f9a10319905af6d0202a3b30c30.1662411799.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Rename set_alloc_info() and kasan_set_free_info() to save_alloc_info() and kasan_save_free_info(). The new names make more sense. Link: https://lkml.kernel.org/r/9f04777a15cb9d96bf00331da98e021d732fe1c9.1662411799.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Patch series "kasan: switch tag-based modes to stack ring from per-object metadata", v3. This series makes the tag-based KASAN modes use a ring buffer for storing stack depot handles for alloc/free stack traces for slab objects instead of per-object metadata. This ring buffer is referred to as the stack ring. On each alloc/free of a slab object, the tagged address of the object and the current stack trace are recorded in the stack ring. On each bug report, if the accessed address belongs to a slab object, the stack ring is scanned for matching entries. The newest entries are used to print the alloc/free stack traces in the report: one entry for alloc and one for free. The advantages of this approach over storing stack trace handles in per-object metadata with the tag-based KASAN modes: - Allows to find relevant stack traces for use-after-free bugs without using quarantine for freed memory. (Currently, if the object was reallocated multiple times, the report contains the latest alloc/free stack traces, not necessarily the ones relevant to the buggy allocation.) - Allows to better identify and mark use-after-free bugs, effectively making the CONFIG_KASAN_TAGS_IDENTIFY functionality always-on. - Has fixed memory overhead. The disadvantage: - If the affected object was allocated/freed long before the bug happened and the stack trace events were purged from the stack ring, the report will have no stack traces. Discussion ========== The proposed implementation of the stack ring uses a single ring buffer for the whole kernel. This might lead to contention due to atomic accesses to the ring buffer index on multicore systems. At this point, it is unknown whether the performance impact from this contention would be significant compared to the slowdown introduced by collecting stack traces due to the planned changes to the latter part, see the section below. For now, the proposed implementation is deemed to be good enough, but this might need to be revisited once the stack collection becomes faster. A considered alternative is to keep a separate ring buffer for each CPU and then iterate over all of them when printing a bug report. This approach requires somehow figuring out which of the stack rings has the freshest stack traces for an object if multiple stack rings have them. Further plans ============= This series is a part of an effort to make KASAN stack trace collection suitable for production. This requires stack trace collection to be fast and memory-bounded. The planned steps are: 1. Speed up stack trace collection (potentially, by using SCS; patches on-hold until steps #2 and #3 are completed). 2. Keep stack trace handles in the stack ring (this series). 3. Add a memory-bounded mode to stack depot or provide an alternative memory-bounded stack storage. 4. Potentially, implement stack trace collection sampling to minimize the performance impact. This patch (of 34): __kasan_metadata_size() calculates the size of the redzone for objects in a slab cache. When accounting for presence of kasan_free_meta in the redzone, this function only compares free_meta_offset with 0. But free_meta_offset could also be equal to KASAN_NO_FREE_META, which indicates that kasan_free_meta is not present at all. Add a comparison with KASAN_NO_FREE_META into __kasan_metadata_size(). Link: https://lkml.kernel.org/r/cover.1662411799.git.andreyknvl@google.com Link: https://lkml.kernel.org/r/c7b316d30d90e5947eb8280f4dc78856a49298cf.1662411799.git.andreyknvl@google.comSigned-off-by:
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Vishal Moola (Oracle) authored
Removes 3 calls to compound_head(). Link: https://lkml.kernel.org/r/20220905214557.868606-1-vishal.moola@gmail.comSigned-off-by:
Vishal Moola (Oracle) <vishal.moola@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by:
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Matthias Goergens authored
Left-shifting past the size of your datatype is undefined behaviour in C. The literal 34 gets the type `int`, and that one is not big enough to be left shifted by 26 bits. An `unsigned` is long enough (on any machine that has at least 32 bits for their ints.) For uniformity, we mark all the literals as unsigned. But it's only really needed for HUGETLB_FLAG_ENCODE_16GB. Thanks to Randy Dunlap for an initial review and suggestion. Link: https://lkml.kernel.org/r/20220905031904.150925-1-matthias.goergens@gmail.comSigned-off-by:
Matthias Goergens <matthias.goergens@gmail.com> Acked-by:
Randy Dunlap <rdunlap@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by:
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Kaixu Xia authored
It is unnecessary to get the number of the running kdamond to judge whether kdamonds are busy. Here we can use the damon_sysfs_kdamond_running() helper and return -EBUSY directly when finding a running kdamond. Meanwhile, merging with the judgement that a kdamond has current sysfs command callback request to make the code more clear. Link: https://lkml.kernel.org/r/1662302166-13216-1-git-send-email-kaixuxia@tencent.comSigned-off-by:
Kaixu Xia <kaixuxia@tencent.com> Reviewed-by:
SeongJae Park <sj@kernel.org> Signed-off-by:
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Li zeming authored
Link: https://lkml.kernel.org/r/20220905020918.3552-1-zeming@nfschina.comSigned-off-by:
Li zeming <zeming@nfschina.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by:
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Matthew Wilcox (Oracle) authored
Remove a call to compound_head() in each of the two callers. Link: https://lkml.kernel.org/r/20220902194653.1739778-58-willy@infradead.orgSigned-off-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by:
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Matthew Wilcox (Oracle) authored
Saves several calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-57-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
This was simply an alias for anon_vma_unlock_read() since 2011. Link: https://lkml.kernel.org/r/20220902194653.1739778-56-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
With all callers now passing in a folio, rename the function and convert all callers. Removes a couple of calls to compound_head() and a reference to page->mapping. Link: https://lkml.kernel.org/r/20220902194653.1739778-55-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Remove a folio->page->folio conversion. Link: https://lkml.kernel.org/r/20220902194653.1739778-54-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Saves many calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-53-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Saves several calls to compound_head() and removes a couple of uses of page->lru. Link: https://lkml.kernel.org/r/20220902194653.1739778-52-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Removes a lot of calls to compound_head(). Also remove a VM_BUG_ON that can never trigger as the PageAnon bit is the bottom bit of page->mapping. Link: https://lkml.kernel.org/r/20220902194653.1739778-51-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Removes one call to compound_head() and a reference to page->mapping. Link: https://lkml.kernel.org/r/20220902194653.1739778-50-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
All callers have now been converted to folio_free_swap() and we can remove this wrapper. Link: https://lkml.kernel.org/r/20220902194653.1739778-49-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
All callers now have a folio, so convert the function to take a folio. Saves a couple of calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-48-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Also convert should_try_to_free_swap() to use a folio. This removes a few calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-47-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Replace three calls to compound_head() with one. Link: https://lkml.kernel.org/r/20220902194653.1739778-46-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Remove a few hidden calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-45-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Saves a lot of calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-44-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Removes many calls to compound_head(). Does not remove the assumption that a folio may not be larger than a PMD. Link: https://lkml.kernel.org/r/20220902194653.1739778-43-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Saves many calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-42-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Removes many calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-41-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Saves several calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-40-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
All callers have now been converted to swap_cache_get_folio(), so we can remove this wrapper. Link: https://lkml.kernel.org/r/20220902194653.1739778-39-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Saves a folio->page->folio conversion. Link: https://lkml.kernel.org/r/20220902194653.1739778-38-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Delay fetching the precise page from the folio until we're in unuse_pte(). Saves many calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-37-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Saves five calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-36-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Saves five calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-35-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
With all callers removed, remove this wrapper function. The flags are now mysteriously called SGP, but I think we can live with that. Link: https://lkml.kernel.org/r/20220902194653.1739778-34-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
shmem_getpage() is being replaced by shmem_get_folio() so use a folio throughout this function. Saves several calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-33-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
shmem_getpage() is being removed, so call its replacement and find the precise page ourselves. Link: https://lkml.kernel.org/r/20220902194653.1739778-32-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Symlinks will never use a large folio, but using the folio API removes a lot of unnecessary folio->page->folio conversions. Link: https://lkml.kernel.org/r/20220902194653.1739778-31-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
While symlinks will always be < PAGE_SIZE, using the folio APIs gets rid of unnecessary calls to compound_head(). Link: https://lkml.kernel.org/r/20220902194653.1739778-30-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Call shmem_get_folio() and use the folio APIs instead of the page APIs. Saves several calls to compound_head() and removes assumptions about the size of a large folio. Link: https://lkml.kernel.org/r/20220902194653.1739778-29-willy@infradead.orgSigned-off-by:
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