- 18 Apr, 2023 40 commits
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Peter Xu authored
Make the handler optionally apply WP bit when resolving page faults for either missing or minor page faults. This moves towards removing global test_uffdio_wp outside of the common code. Link: https://lkml.kernel.org/r/20230412164341.328618-1-peterx@redhat.comSigned-off-by:
Peter Xu <peterx@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Zach O'Keefe <zokeefe@google.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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Peter Xu authored
Prepare for adding more fields into the struct. Link: https://lkml.kernel.org/r/20230412164337.328607-1-peterx@redhat.comSigned-off-by:
Mike Rapoport (IBM) <rppt@kernel.org> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zach O'Keefe <zokeefe@google.com> Signed-off-by:
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Peter Xu authored
hpage_size was wrongly used. Sometimes it means hugetlb default size, sometimes it was used as thp size. Remove the global variable and use the right one at each place. Link: https://lkml.kernel.org/r/20230412164333.328596-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
Drop it by creating the memfd dynamically in the tests. Link: https://lkml.kernel.org/r/20230412164331.328584-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
Add one simple test for UFFDIO_API. With that, I also added a bunch of small but handy helpers along the way. Link: https://lkml.kernel.org/r/20230412164257.328375-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
Provide two helpers to open an uffd handle. Drop the error checks around SKIPs because it's inside an errexit() anyway, which IMHO doesn't really help much if the test will not continue. Link: https://lkml.kernel.org/r/20230412164254.328335-1-peterx@redhat.comSigned-off-by:
David Hildenbrand <david@redhat.com> Reviewed-by:
Axel Rasmussen <axelrasmussen@google.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Zach O'Keefe <zokeefe@google.com> Signed-off-by:
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Peter Xu authored
Add two helpers to register/unregister to an uffd. Use them to drop duplicate codes. This patch also drops assert_expected_ioctls_present() and get_expected_ioctls(). Reasons: - It'll need a lot of effort to pass test_type==HUGETLB into it from the upper, so it's the simplest way to get rid of another global var - The ioctls returned in UFFDIO_REGISTER is hardly useful at all, because any app can already detect kernel support on any ioctl via its corresponding UFFD_FEATURE_*. The check here is for sanity mostly but it's probably destined no user app will even use it. - It's not friendly to one future goal of uffd to run on old kernels, the problem is get_expected_ioctls() compiles against UFFD_API_RANGE_IOCTLS, which is a value that can change depending on where the test is compiled, rather than reflecting what the kernel underneath has. It means it'll report false negatives on old kernels so it's against our will. So let's make our lives easier. [peterx@redhat.com; tools/testing/selftests/mm/hugepage-mremap.c: add headers] Link: https://lkml.kernel.org/r/ZDxrvZh/cw357D8P@x1n Link: https://lkml.kernel.org/r/20230412164247.328293-1-peterx@redhat.comSigned-off-by: -
Peter Xu authored
In many ways it's weird and unwanted to keep all the tests in the same userfaultfd.c at least when still in the current way. For example, it doesn't make much sense to run the stress test for each method we can create an userfaultfd handle (either via syscall or /dev/ node). It's a waste of time running this twice for the whole stress as the stress paths are the same, only the open path is different. It's also just weird to need to manually specify different types of memory to run all unit tests for the userfaultfd interface. We should be able to just run a single program and that should go through all functional uffd tests without running the stress test at all. The stress test was more for torturing and finding race conditions. We don't want to wait for stress to finish just to regress test a functional test. When we start to pile up more things on top of the same file and same functions, things start to go a bit chaos and the code is just harder to maintain too with tons of global variables. This patch creates a new test uffd-unit-tests to keep userfaultfd unit tests in the future, currently empty. Meanwhile rename the old userfaultfd.c test to uffd-stress.c. Link: https://lkml.kernel.org/r/20230412164244.328270-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
Move common utility functions into uffd-common.[ch] files from the original userfaultfd.c. This prepares for a split of userfaultfd.c into two tests: one to only cover the old but powerful stress test, the other one covers all the functional tests. This movement is kind of a brute-force effort for now, with light touch-ups but nothing should really change. There's chances to optimize more, but let's leave that for later. Link: https://lkml.kernel.org/r/20230412164241.328259-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
The idea was trying to flip this var in the alarm handler from time to time to test -EEXIST of UFFDIO_ZEROPAGE, but firstly it's only used in the zeropage test so probably only used once, meanwhile we passed "retry==false" so it'll never got tested anyway. Drop both sides so we always test UFFDIO_ZEROPAGE retries if has_zeropage is set (!hugetlb). One more thing to do is doing UFFDIO_REGISTER for the alias buffer too, because otherwise the test won't even pass! We were just lucky that this test never really got ran at all. Link: https://lkml.kernel.org/r/20230412164238.328238-1-peterx@redhat.comSigned-off-by:
Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by:
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Peter Xu authored
Make the check as simple as "test_type == TEST_HUGETLB" because that's the only mem that doesn't support ZEROPAGE. Link: https://lkml.kernel.org/r/20230412164234.328168-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
Meanwhile drop pagemap_read_vaddr(). Link: https://lkml.kernel.org/r/20230412164231.328157-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
We've got the macros in uffd-stress.c, move it over and use it in vm_util.h. Link: https://lkml.kernel.org/r/20230412164227.328145-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
There're already 3 same definitions of the three functions. Move it into vm_util.[ch]. Link: https://lkml.kernel.org/r/20230412164223.328134-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
We do have plenty of files that want to link against vm_util.c. Just make it simple by linking it always. Link: https://lkml.kernel.org/r/20230412164220.328123-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
TEST_GEN_PROGS and TEST_GEN_FILES are used randomly in the mm/Makefile to specify programs that need to build. Logically all these binaries should all fall into TEST_GEN_PROGS. Replace those TEST_GEN_FILES with TEST_GEN_PROGS, so that we can reference all the tests easily later. [peterx@redhat.com: tools/testing/selftests/mm/Makefile: don't wipe out TEST_GEN_PROGS] Link: https://lkml.kernel.org/r/ZDxrvZh/cw357D8P@x1n Link: https://lkml.kernel.org/r/20230412164218.328104-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
There're two util headers under mm/ kselftest. Merge one with another. It turns out util.h is the easy one to move. When merging, drop PAGE_SIZE / PAGE_SHIFT because they're unnecessary wrappers to page_size() / page_shift(), meanwhile rename them to psize() and pshift() so as to not conflict with some existing definitions in some test files that includes vm_util.h. Link: https://lkml.kernel.org/r/20230412164120.327731-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
Dump a summary after running whatever test specified. Useful for human runners to identify any kind of failures (besides exit code). Link: https://lkml.kernel.org/r/20230412164117.327720-1-peterx@redhat.comSigned-off-by:
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Peter Xu authored
Patch series "selftests/mm: Split / Refactor userfault test", v2. This patchset splits userfaultfd.c into two tests: - uffd-stress: the "vanilla", old and powerful stress test - uffd-unit-tests: all the unit tests will be moved here This is on my todo list for a long time but I never did it for real. The uffd test is growing into a small and cute monster. I start to notice it's going harder to maintain such a test and make it useful. A few issues I found when looking at userfaultfd test: - We have a bunch of unit tests in userfaultfd.c, but they always need to be run only after a stress type. No way to not do it. - We can only run an unit test for one memory type only, if we want to do a quick smoke test to check regressions, there's no good way. The best to come currently is "bash ./run_vmtests.sh -t userfaultfd" thanks to the most recent changes to run_vmtests.sh on tagging. Still, that needs to run the stress tests always and hard to see what's wrong. - It's hard to add a new unit test to userfaultfd.c, we don't really know what's happening, not until we mostly read the whole file. - We did a bunch of useless tests, e.g. we run twice the whole suite of stress test just to verify both syscall and /dev/userfaultfd. They're all using userfaultfd_new() to create the handle, everything should really be the same underneath. One simple unit test should cover that! - We have tens of global variables in one file but shared with all the tests. Some of them are not suitable to be a global var from maintainance pov. It enforces every unit test to consider how these vars affects the stress test and vice versa, but that's logically not necessary. - Userfaultfd test is not friendly to old kernels. Mostly it only works on the latest kernel tree. It's preferrable to be run on all kernels and properly report what's missing. I'll stop here, I feel like I can still list some.. This patchset should resolve all issues above, and actually we can do even more on top. I stopped doing that until I found I already got 29 patches and 2000+ LOC changes. That's already a patchset terrible enough so we should move in small steps. After the whole set applied, "./run_vmtests.sh -t userfaultfd" looks like this: ===8<=== vm.nr_hugepages = 1024 ------------------------- running ./uffd-unit-tests ------------------------- Testing UFFDIO_API (with syscall)... done Testing UFFDIO_API (with /dev/userfaultfd)... done Testing register-ioctls on anon... done Testing register-ioctls on shmem... done Testing register-ioctls on shmem-private... done Testing register-ioctls on hugetlb... done Testing register-ioctls on hugetlb-private... done Testing zeropage on anon... done Testing zeropage on shmem... done Testing zeropage on shmem-private... done Testing zeropage on hugetlb... done Testing zeropage on hugetlb-private... done Testing pagemap on anon... done Testing wp-unpopulated on anon... done Testing minor on shmem... done Testing minor on hugetlb... done Testing minor-wp on shmem... done Testing minor-wp on hugetlb... done Testing minor-collapse on shmem... done Testing sigbus on anon... done Testing sigbus on shmem... done Testing sigbus on shmem-private... done Testing sigbus on hugetlb... done Testing sigbus on hugetlb-private... done Testing sigbus-wp on anon... done Testing sigbus-wp on shmem... done Testing sigbus-wp on shmem-private... done Testing sigbus-wp on hugetlb... done Testing sigbus-wp on hugetlb-private... done Testing events on anon... done Testing events on shmem... done Testing events on shmem-private... done Testing events on hugetlb... done Testing events on hugetlb-private... done Testing events-wp on anon... done Testing events-wp on shmem... done Testing events-wp on shmem-private... done Testing events-wp on hugetlb... done Testing events-wp on hugetlb-private... done Userfaults unit tests: pass=39, skip=0, fail=0 (total=39) [PASS] -------------------------------- running ./uffd-stress anon 20 16 -------------------------------- nr_pages: 5120, nr_pages_per_cpu: 640 bounces: 15, mode: rnd racing ver poll, userfaults: 345 missing (26+48+61+102+30+12+59+7) 1596 wp (120+139+317+346+215+67+306+86) [...] [PASS] ------------------------------------ running ./uffd-stress hugetlb 128 32 ------------------------------------ nr_pages: 64, nr_pages_per_cpu: 8 bounces: 31, mode: rnd racing ver poll, userfaults: 29 missing (6+6+6+5+4+2+0+0) 104 wp (20+19+22+18+7+12+5+1) [...] [PASS] -------------------------------------------- running ./uffd-stress hugetlb-private 128 32 -------------------------------------------- nr_pages: 64, nr_pages_per_cpu: 8 bounces: 31, mode: rnd racing ver poll, userfaults: 33 missing (12+9+7+0+5+0+0+0) 111 wp (24+25+14+14+11+17+5+1) [...] [PASS] --------------------------------- running ./uffd-stress shmem 20 16 --------------------------------- nr_pages: 5120, nr_pages_per_cpu: 640 bounces: 15, mode: rnd racing ver poll, userfaults: 247 missing (15+17+34+60+81+37+3+0) 2038 wp (180+114+276+400+381+318+165+204) [...] [PASS] ----------------------------------------- running ./uffd-stress shmem-private 20 16 ----------------------------------------- nr_pages: 5120, nr_pages_per_cpu: 640 bounces: 15, mode: rnd racing ver poll, userfaults: 235 missing (52+29+55+56+13+9+16+5) 2849 wp (218+406+461+531+328+284+430+191) [...] [PASS] SUMMARY: PASS=6 SKIP=0 FAIL=0 ===8<=== The output may be different if we miss some features (e.g., hugetlb not allocated, old kernel, less privilege of uffd handle), but they should show up with good reasons. E.g., I tried to run the unit test on my Fedora kernel and it gives me: ===8<=== UFFDIO_API (with syscall)... failed [reason: UFFDIO_API should fail with wrong api but didn't] UFFDIO_API (with /dev/userfaultfd)... skipped [reason: cannot open userfaultfd handle] zeropage on anon... done zeropage on shmem... done zeropage on shmem-private... done zeropage-hugetlb on hugetlb... done zeropage-hugetlb on hugetlb-private... done pagemap on anon... pagemap on anon... pagemap on anon... done wp-unpopulated on anon... skipped [reason: feature missing] minor on shmem... done minor on hugetlb... done minor-wp on shmem... skipped [reason: feature missing] minor-wp on hugetlb... skipped [reason: feature missing] minor-collapse on shmem... done sigbus on anon... skipped [reason: possible lack of priviledge] sigbus on shmem... skipped [reason: possible lack of priviledge] sigbus on shmem-private... skipped [reason: possible lack of priviledge] sigbus on hugetlb... skipped [reason: possible lack of priviledge] sigbus on hugetlb-private... skipped [reason: possible lack of priviledge] sigbus-wp on anon... skipped [reason: possible lack of priviledge] sigbus-wp on shmem... skipped [reason: possible lack of priviledge] sigbus-wp on shmem-private... skipped [reason: possible lack of priviledge] sigbus-wp on hugetlb... skipped [reason: possible lack of priviledge] sigbus-wp on hugetlb-private... skipped [reason: possible lack of priviledge] events on anon... skipped [reason: possible lack of priviledge] events on shmem... skipped [reason: possible lack of priviledge] events on shmem-private... skipped [reason: possible lack of priviledge] events on hugetlb... skipped [reason: possible lack of priviledge] events on hugetlb-private... skipped [reason: possible lack of priviledge] events-wp on anon... skipped [reason: possible lack of priviledge] events-wp on shmem... skipped [reason: possible lack of priviledge] events-wp on shmem-private... skipped [reason: possible lack of priviledge] events-wp on hugetlb... skipped [reason: possible lack of priviledge] events-wp on hugetlb-private... skipped [reason: possible lack of priviledge] Userfaults unit tests: pass=9, skip=24, fail=1 (total=34) ===8<=== Patch layout: - Revert "userfaultfd: don't fail on unrecognized features" Something I found when I got the UFFDIO_API test below. Axel, I still propose to revert it as a whole, but feel free to continue the discussion from the original patch thread. - selftests/mm: Update .gitignore with two missing tests - selftests/mm: Dump a summary in run_vmtests.sh - selftests/mm: Merge util.h into vm_util.h - selftests/mm: Use TEST_GEN_PROGS where proper - selftests/mm: Link vm_util.c always - selftests/mm: Merge default_huge_page_size() into one - selftests/mm: Use PM_* macros in vm_utils.h - selftests/mm: Reuse pagemap_get_entry() in vm_util.h - selftests/mm: Test UFFDIO_ZEROPAGE only when !hugetlb - selftests/mm: Drop test_uffdio_zeropage_eexist Until here, all cleanups here and there. I wanted to keep going, but I found that maybe it'll take a few more days to split the test. Hence I did a split starting from the next one, so we have a working thing first. - selftests/mm: Create uffd-common.[ch] - selftests/mm: Split uffd tests into uffd-stress and uffd-unit-tests This did the major brute force split of common codes into uffd-common.[ch]. That'll be the so far common base for stress and unit tests. Then a new unit test is created. - selftests/mm: uffd_[un]register() - selftests/mm: uffd_open_{dev|sys}() - selftests/mm: UFFDIO_API test This patch hides here to start writting the 1st unit test with UFFDIO_API, also detection of userfaultfd privileges. - selftests/mm: Drop global mem_fd in uffd tests - selftests/mm: Drop global hpage_size in uffd tests - selftests/mm: Rename uffd_stats to uffd_args - selftests/mm: Let uffd_handle_page_fault() takes wp parameter - selftests/mm: Allow allocate_area() to fail properly Some further cleanup that I noticed otherwise hard to move the tests. - selftests/mm: Add framework for uffd-unit-test The major patch provides the framework for most of the rest unit tests. - selftests/mm: Move uffd pagemap test to unit test - selftests/mm: Move uffd minor test to unit test - selftests/mm: Move uffd sig/events tests into uffd unit tests - selftests/mm: Move zeropage test into uffd unit tests Move unit tests and suite them into the new file. - selftests/mm: Workaround no way to detect uffd-minor + wp - selftests/mm: Allow uffd test to skip properly with no privilege - selftests/mm: Drop sys/dev test in uffd-stress test - selftests/mm: Add shmem-private test to uffd-stress A bunch of changes to do better on error reportings, and add shmem-private to the stress test which was long missing. - selftests/mm: Add uffdio register ioctls test One more patch to test uffdio_register.ioctls. This patch (of 30): Update .gitignore with two missing tests. Link: https://lkml.kernel.org/r/20230412163922.327282-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20230412164114.327709-1-peterx@redhat.comSigned-off-by: -
Haifeng Xu authored
The difference between sc->nr_reclaimed and nr_reclaimed is computed three times. Introduce a new variable to record the value, so it only needs to be computed once. Link: https://lkml.kernel.org/r/20230411061757.12041-1-haifeng.xu@shopee.comSigned-off-by:
Haifeng Xu <haifeng.xu@shopee.com> Reviewed-by:
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Pankaj Raghav authored
Use folios in the bio end_io handler. This conversion does the appropriate handling on the folios in the respective end_io callback and removes the call to page_endio(), which is soon to be removed. Link: https://lkml.kernel.org/r/20230411122920.30134-4-p.raghav@samsung.comSigned-off-by:
Pankaj Raghav <p.raghav@samsung.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Martin Brandenburg <martin@omnibond.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mike Marshall <hubcap@omnibond.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by:
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Pankaj Raghav authored
Split the submit_bio() and bio end_io handler for reads and writes similar to other aops. This is a prep patch before we convert end_io handlers to use folios. Link: https://lkml.kernel.org/r/20230411122920.30134-3-p.raghav@samsung.comSigned-off-by:
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Pankaj Raghav authored
Patch series "remove page_endio()", v3. It was decided to remove the page_endio() as per the previous RFC discussion[1] of this series and move that functionality into the caller itself. One of the side benefit of doing that is the callers have been modified to directly work on folios as page_endio() already worked on folios. As Christoph is doing ZRAM cleanups[4] which will get rid of page_endio() function usage, I removed the final patch that removes page_endio()[5]. I will send it separately after rc-1 once the zram cleanups are merged. mpage changes were tested with a simple boot testing and running a fio workload on ext2 filesystem. orangefs was tested by Mike Marshall (No code changes since he tested). This patch (of 3): Convert orangefs_readahead() from using struct page to struct folio. This conversion removes the call to page_endio() which is soon to be removed, and simplifies the final page handling. The page error flags is not required to be set in the error case as orangefs doesn't depend on them. Link: https://lkml.kernel.org/r/20230411122920.30134-1-p.raghav@samsung.com Link: https://lkml.kernel.org/r/20230411122920.30134-2-p.raghav@samsung.com Link: https://lore.kernel.org/linux-mm/ZBHcl8Pz2ULb4RGD@infradead.org/ [1] Link: https://lore.kernel.org/linux-mm/20230322135013.197076-1-p.raghav@samsung.com/ [2] Link: https://lore.kernel.org/linux-mm/8adb0770-6124-e11f-2551-6582db27ed32@samsung.com/ [3] Link: https://lore.kernel.org/linux-block/20230404150536.2142108-1-hch@lst.de/T/#t [4] Link: https://lore.kernel.org/lkml/20230403132221.94921-6-p.raghav@samsung.com/ [5] Signed-off-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by:
Mike Marshall <hubcap@omnibond.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Martin Brandenburg <martin@omnibond.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by:
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David Hildenbrand authored
mm/huge_memory: conditionally call maybe_mkwrite() and drop pte_wrprotect() in __split_huge_pmd_locked() No need to call maybe_mkwrite() to then wrprotect if the source PMD was not writable. It's worth nothing that this now allows for PTEs to be writable even if the source PMD was not writable: if vma->vm_page_prot includes write permissions. As documented in commit 931298e1 ("mm/userfaultfd: rely on vma->vm_page_prot in uffd_wp_range()"), any mechanism that intends to have pages wrprotected (COW, writenotify, mprotect, uffd-wp, softdirty, ...) has to properly adjust vma->vm_page_prot upfront, to not include write permissions. If vma->vm_page_prot includes write permissions, the PTE/PMD can be writable as default. This now mimics the handling in mm/migrate.c:remove_migration_pte() and in mm/huge_memory.c:remove_migration_pmd(), which has been in place for a long time (except that 96a9c287 ("mm/migrate: fix wrongly apply write bit after mkdirty on sparc64") temporarily changed it). Link: https://lkml.kernel.org/r/20230411142512.438404-7-david@redhat.comSigned-off-by:
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David Hildenbrand authored
This reverts commit 624a2c94 ("Partly revert "mm/thp: carry over dirty bit when thp splits on pmd"") and the fixup in commit e833bc50 ("mm/thp: re-apply mkdirty for small pages after split"). Now that sparc64 mkdirty handling is fixed and no longer sets a PTE/PMD writable that shouldn't be writable, let's revert the temporary fix and remove the stale comment. The mkdirty mm selftest still passes with this change on sparc64. Note that loongarch handling was fixed in commit bf2f34a5 ("LoongArch: Set _PAGE_DIRTY only if _PAGE_WRITE is set in {pmd,pte}_mkdirty()") Link: https://lkml.kernel.org/r/20230411142512.438404-6-david@redhat.comSigned-off-by:
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David Hildenbrand authored
This reverts commit 96a9c287 ("mm/migrate: fix wrongly apply write bit after mkdirty on sparc64"). Now that sparc64 mkdirty handling is fixed and no longer sets a PTE/PMD writable that shouldn't be writable, let's revert the temporary fix. The mkdirty mm selftest still passes with this change on sparc64. Note that loongarch handling was fixed in commit bf2f34a5 ("LoongArch: Set _PAGE_DIRTY only if _PAGE_WRITE is set in {pmd,pte}_mkdirty()"). Link: https://lkml.kernel.org/r/20230411142512.438404-5-david@redhat.comSigned-off-by:
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David Hildenbrand authored
On sparc64, there is no HW modified bit, therefore, SW tracks via a SW bit if the PTE is dirty via pte_mkdirty(). However, pte_mkdirty() currently also unconditionally sets the HW writable bit, which is wrong. pte_mkdirty() is not supposed to make a PTE actually writable, unless the SW writable bit -- pte_write() -- indicates that the PTE is not write-protected. Fortunately, sparc64 also defines a SW writable bit. For example, this already turned into a problem in the context of THP splitting as documented in commit 624a2c94 ("Partly revert "mm/thp: carry over dirty bit when thp splits on pmd""), and for page migration, as documented in commit 96a9c287 ("mm/migrate: fix wrongly apply write bit after mkdirty on sparc64"). Also, we might want to use the dirty PTE bit in the context of KSM with shared zeropage [1], whereby setting the page writable would be problematic. But more general, any code that might end up setting a PTE/PMD dirty inside a VM without write permissions is possibly broken, Before this commit (sun4u in QEMU): root@debian:~/linux/tools/testing/selftests/mm# ./mkdirty # [INFO] detected THP size: 8192 KiB TAP version 13 1..6 # [INFO] PTRACE write access not ok 1 SIGSEGV generated, page not modified # [INFO] PTRACE write access to THP not ok 2 SIGSEGV generated, page not modified # [INFO] Page migration ok 3 SIGSEGV generated, page not modified # [INFO] Page migration of THP ok 4 SIGSEGV generated, page not modified # [INFO] PTE-mapping a THP ok 5 SIGSEGV generated, page not modified # [INFO] UFFDIO_COPY not ok 6 SIGSEGV generated, page not modified Bail out! 3 out of 6 tests failed # Totals: pass:3 fail:3 xfail:0 xpass:0 skip:0 error:0 Test #3,#4,#5 pass ever since we added some MM workarounds, the underlying issue remains. Let's fix the remaining issues and prepare for reverting the workarounds by setting the HW writable bit only if both, the SW dirty bit and the SW writable bit are set. We have to move pte_dirty() and pte_write() up. The code patching mechanism and handling constants > 22bit is a bit special on sparc64. The ASM logic in pte_mkdirty() and pte_mkwrite() match the logic in pte_mkold() to create the mask depending on the machine type. The ASM logic in __pte_mkhwwrite() matches the logic in pte_present(), just using an "or" instead of an "and" instruction. With this commit (sun4u in QEMU): root@debian:~/linux/tools/testing/selftests/mm# ./mkdirty # [INFO] detected THP size: 8192 KiB TAP version 13 1..6 # [INFO] PTRACE write access ok 1 SIGSEGV generated, page not modified # [INFO] PTRACE write access to THP ok 2 SIGSEGV generated, page not modified # [INFO] Page migration ok 3 SIGSEGV generated, page not modified # [INFO] Page migration of THP ok 4 SIGSEGV generated, page not modified # [INFO] PTE-mapping a THP ok 5 SIGSEGV generated, page not modified # [INFO] UFFDIO_COPY ok 6 SIGSEGV generated, page not modified # Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0 This handling seems to have been in place forever. [1] https://lkml.kernel.org/r/533a7c3d-3a48-b16b-b421-6e8386e0b142@redhat.com Link: https://lkml.kernel.org/r/20230411142512.438404-4-david@redhat.com Fixes: 1da177e4 ("Linux-2.6.12-rc2") Signed-off-by:
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David Hildenbrand authored
Let's add some tests that trigger (pte|pmd)_mkdirty on VMAs without write permissions. If an architecture implementation is wrong, we might accidentally set the PTE/PMD writable and allow for write access in a VMA without write permissions. The tests include reproducers for the two issues recently discovered and worked-around in core-MM for now: (1) commit 624a2c94 ("Partly revert "mm/thp: carry over dirty bit when thp splits on pmd"") (2) commit 96a9c287 ("mm/migrate: fix wrongly apply write bit after mkdirty on sparc64") In addition, some other tests that reveal further issues. All tests pass under x86_64: ./mkdirty # [INFO] detected THP size: 2048 KiB TAP version 13 1..6 # [INFO] PTRACE write access ok 1 SIGSEGV generated, page not modified # [INFO] PTRACE write access to THP ok 2 SIGSEGV generated, page not modified # [INFO] Page migration ok 3 SIGSEGV generated, page not modified # [INFO] Page migration of THP ok 4 SIGSEGV generated, page not modified # [INFO] PTE-mapping a THP ok 5 SIGSEGV generated, page not modified # [INFO] UFFDIO_COPY ok 6 SIGSEGV generated, page not modified # Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0 But some fail on sparc64: ./mkdirty # [INFO] detected THP size: 8192 KiB TAP version 13 1..6 # [INFO] PTRACE write access not ok 1 SIGSEGV generated, page not modified # [INFO] PTRACE write access to THP not ok 2 SIGSEGV generated, page not modified # [INFO] Page migration ok 3 SIGSEGV generated, page not modified # [INFO] Page migration of THP ok 4 SIGSEGV generated, page not modified # [INFO] PTE-mapping a THP ok 5 SIGSEGV generated, page not modified # [INFO] UFFDIO_COPY not ok 6 SIGSEGV generated, page not modified Bail out! 3 out of 6 tests failed # Totals: pass:3 fail:3 xfail:0 xpass:0 skip:0 error:0 Reverting both above commits makes all tests fail on sparc64: ./mkdirty # [INFO] detected THP size: 8192 KiB TAP version 13 1..6 # [INFO] PTRACE write access not ok 1 SIGSEGV generated, page not modified # [INFO] PTRACE write access to THP not ok 2 SIGSEGV generated, page not modified # [INFO] Page migration not ok 3 SIGSEGV generated, page not modified # [INFO] Page migration of THP not ok 4 SIGSEGV generated, page not modified # [INFO] PTE-mapping a THP not ok 5 SIGSEGV generated, page not modified # [INFO] UFFDIO_COPY not ok 6 SIGSEGV generated, page not modified Bail out! 6 out of 6 tests failed # Totals: pass:0 fail:6 xfail:0 xpass:0 skip:0 error:0 The tests are useful to detect other problematic archs, to verify new arch fixes, and to stop such issues from reappearing in the future. For now, we don't add any hugetlb tests. Link: https://lkml.kernel.org/r/20230411142512.438404-3-david@redhat.comSigned-off-by:
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David Hildenbrand authored
Patch series "mm: (pte|pmd)_mkdirty() should not unconditionally allow for write access". This is the follow-up on [1], adding selftests (testing for known issues we added workarounds for and other issues that haven't been fixed yet), fixing sparc64, reverting the workarounds, and perform one cleanup. The patch from [1] was modified slightly (updated/extended patch description, dropped one unnecessary NOP instruction from the ASM in __pte_mkhwwrite()). Retested on x86_64 and sparc64 (sun4u in QEMU). I scanned most architectures to make sure their (pte|pmd)_mkdirty() handling is correct. To be sure, we can run the selftests and find out if other architectures are still affectes (loongarch was fixed recently as well). Based on master for now. I don't expect surprises regarding mm-tress, but I can rebase if there are any problems. This patch (of 6): The COW selftest can deal with THP not being configured. So move error handling of read_pmd_pagesize() into the callers such that we can reuse it in the COW selftest. Link: https://lkml.kernel.org/r/20230411142512.438404-1-david@redhat.com Link: https://lkml.kernel.org/r/20221212130213.136267-1-david@redhat.com [1] Link: https://lkml.kernel.org/r/20230411142512.438404-2-david@redhat.comSigned-off-by:
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Christoph Hellwig authored
Propagate read errors to the caller instead of dropping them on the floor, and stop returning the somewhat dangerous 1 on success from read_from_bdev*. Link: https://lkml.kernel.org/r/20230411171459.567614-18-hch@lst.deSigned-off-by:
Sergey Senozhatsky <senozhatsky@chromium.org> Acked-by:
Minchan Kim <minchan@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by:
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Christoph Hellwig authored
Currently nothing waits for the synchronous reads before accessing the data. Switch them to an on-stack bio and submit_bio_wait to make sure the I/O has actually completed when the work item has been flushed. This also removes the call to page_endio that would unlock a page that has never been locked. Drop the partial_io/sync flag, as chaining only makes sense for the asynchronous reads of the entire page. Link: https://lkml.kernel.org/r/20230411171459.567614-17-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
bio_alloc will never return a NULL bio when it is allowed to sleep, and adding a single page to bio with a single vector also can't fail, so switch to the asserting __bio_add_page variant and drop the error returns. Link: https://lkml.kernel.org/r/20230411171459.567614-16-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
read_from_bdev always reads a whole page, so pass a page to it instead of the bvec and remove the now pointless zram_bvec_read_from_bdev wrapper. Link: https://lkml.kernel.org/r/20230411171459.567614-15-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
Split the read/modify/write case into a separate helper. Link: https://lkml.kernel.org/r/20230411171459.567614-14-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
__zram_bvec_write only extracts the page from __zram_bvec_write and always expects a full page of input. Pass the page directly instead of the bvec and rename the function to zram_write_page. Link: https://lkml.kernel.org/r/20230411171459.567614-13-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
Split the partial read into a separate helper. Link: https://lkml.kernel.org/r/20230411171459.567614-12-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
writeback_store always reads a full page, so just call zram_read_page directly and bypass the boune buffer handling. Link: https://lkml.kernel.org/r/20230411171459.567614-11-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
__zram_bvec_read doesn't get passed a bvec, but always read a whole page. Rename it to make the usage more clear. Link: https://lkml.kernel.org/r/20230411171459.567614-10-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
There is no point in allocation a highmem page when we instantly need to copy from it. Link: https://lkml.kernel.org/r/20230411171459.567614-9-hch@lst.deSigned-off-by:
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Christoph Hellwig authored
Instead of having an outer loop in __zram_make_request and then branch out for reads vs writes for each loop iteration in zram_bvec_rw, split the main handler into separat zram_bio_read and zram_bio_write handlers that also include the functionality formerly in zram_bvec_rw. Link: https://lkml.kernel.org/r/20230411171459.567614-8-hch@lst.deSigned-off-by:
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