From: Jeff Xu <jeffxu@xxxxxxxxxx> Two fixes for madvise(MADV_DONTNEED) when sealed. For PROT_NONE mappings, the previous blocking of madvise(MADV_DONTNEED) is unnecessary. As PROT_NONE already prohibits memory access, madvise(MADV_DONTNEED) should be allowed to proceed in order to free the page. For file-backed, private, read-only memory mappings, we previously did not block the madvise(MADV_DONTNEED). This was based on the assumption that the memory's content, being file-backed, could be retrieved from the file if accessed again. However, this assumption failed to consider scenarios where a mapping is initially created as read-write, modified, and subsequently changed to read-only. The newly introduced VM_WASWRITE flag addresses this oversight. Jeff Xu (2): mseal: Two fixes for madvise(MADV_DONTNEED) when sealed selftest/mseal: Add tests for madvise include/linux/mm.h | 2 + mm/mprotect.c | 3 + mm/mseal.c | 42 +++++++-- tools/testing/selftests/mm/mseal_test.c | 118 +++++++++++++++++++++++- 4 files changed, 157 insertions(+), 8 deletions(-) -- 2.47.0.rc1.288.g06298d1525-goog
