From ce7fd293b342d2ec7d88e6b72f3a1c44a66bbadf Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Tue, 5 Nov 2019 21:16:48 -0800 Subject: [PATCH] mm/khugepaged: fix might_sleep() warn with CONFIG_HIGHPTE=y MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit I got some khugepaged spew on a 32bit x86: BUG: sleeping function called from invalid context at include/linux/mmu_notifier.h:346 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 25, name: khugepaged INFO: lockdep is turned off. CPU: 1 PID: 25 Comm: khugepaged Not tainted 5.4.0-rc5-elk+ #206 Hardware name: System manufacturer P5Q-EM/P5Q-EM, BIOS 2203 07/08/2009 Call Trace: dump_stack+0x66/0x8e ___might_sleep.cold.96+0x95/0xa6 __might_sleep+0x2e/0x80 collapse_huge_page.isra.51+0x5ac/0x1360 khugepaged+0x9a9/0x20f0 kthread+0xf5/0x110 ret_from_fork+0x2e/0x38 Looks like it's due to CONFIG_HIGHPTE=y pte_offset_map()->kmap_atomic() vs. mmu_notifier_invalidate_range_start(). Let's do the naive approach and just reorder the two operations. Link: http://lkml.kernel.org/r/20191029201513.GG1208@intel.com Fixes: 8b5f461ebd1003 ("mm/mmu_notifiers: annotate with might_sleep()") Signed-off-by: Ville Syrjl Reviewed-by: Andrew Morton Acked-by: Kirill A. Shutemov Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Jérôme Glisse Cc: Ralph Campbell Cc: Ira Weiny Cc: Jason Gunthorpe Cc: Daniel Vetter Cc: Andrea Arcangeli Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/khugepaged.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 0a1b4b484ac5b..f05d27b7183dc 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1028,12 +1028,13 @@ static void collapse_huge_page(struct mm_struct *mm, anon_vma_lock_write(vma->anon_vma); - pte = pte_offset_map(pmd, address); - pte_ptl = pte_lockptr(mm, pmd); - mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, address, address + HPAGE_PMD_SIZE); mmu_notifier_invalidate_range_start(&range); + + pte = pte_offset_map(pmd, address); + pte_ptl = pte_lockptr(mm, pmd); + pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ /* * After this gup_fast can't run anymore. This also removes -- 2.39.5