On Thu, Aug 20, 2026 at 08:09:12PM -0400, Zi Yan wrote: > On Thu Aug 20, 2026 at 5:26 PM EDT, Yeoreum Yun wrote: > >> On Thu Aug 20, 2026 at 3:40 PM EDT, Yeoreum Yun wrote: > >> > Since glibc commit 321e1fc73f (“malloc: Enable 2MB THP by default on > >> > AArch64”), > >> > glibc may call madvise(MADV_HUGEPAGE) for sufficiently large allocations > >> > made by memalign(). > > I just googled the commit and find that Dev did that. ;) > > >> > > >> > The underlying VMA may start at a different address from the aligned > >> > address returned by memalign(). Furthermore, a subsequent > >> > madvise(MADV_HUGEPAGE) call does not split the VMA because the flag is > >> > already set. > >> > > >> > This causes split_huge_page_test to fail because the check_huge_xxx() > >> > helpers incorrectly require the address returned by memalign() to > >> > match the VMA start address reported in /proc/self/smaps. > >> > > >> > Fix this by using /proc/self/pagemap and /proc/kpageflags instead of > >> > /proc/self/smaps to detect huge pages and change the meaning of > >> > check_huge_xxx()'s nr_hpages argument: > >> > >> Have you checked Baolin's patches[1] in mm-new? They resue > >> gather_after_split_folio_orders() to reimplement check_huge_xxx(), also > >> based on pagemap and kpageflags. Does it fix the issue? > >> > >> [1] > >> https://lore.kernel.org/all/[email protected]/ > >> > > > > Unfortunately, No. since __check_pmd_huge() in check_huge_xxx() still use > > /proc/self/smaps [1] for pmd THP, it still has problem though ths patch > > series applied. > > > > [1] > > https://lore.kernel.org/all/56b16691f605426b33b5cf47319233de6127a6b3.1785985999.git.baolin.w...@linux.alibaba.com/ > > In that case, is it possible to use and extend check_large_folios() for > all check_huge_xxx()? You still need pagemap_scan_get_categories() to > check PAGE_IS_HUGE to identify huge mappings. Or at least > check_huge_xxx() in your patch can share most of the code.
Agree. but TBH, I think check_large_folios() can replace checking PAGE_IS_HUGE and keep the later part to check wehther PAGE_IS_FILE and SWAPBACKED according to check_huge_xxx(). BTW, Should I do this after [1] is merged into mm-unstable? > BTW, in your check_huge_shmem(), expect_huge seems to be inverted > compared to other check_huge_xxx(). Yes. I've noticed. this was my typo while I change the variable name... Thanks! [1] https://lore.kernel.org/all/[email protected]/ > > -- > Best Regards, > Yan, Zi > -- Sincerely, Yeoreum Yun
