From: James Morse Date: Sat, 8 Oct 2016 00:00:06 +0000 (-0700) Subject: fs/proc/task_mmu.c: make the task_mmu walk_page_range() limit in clear_refs_write... X-Git-Tag: v4.9-rc1~73^2~62 X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=0f30206bf2a42e278c2cec32e4b722626458c75b fs/proc/task_mmu.c: make the task_mmu walk_page_range() limit in clear_refs_write() obvious Trying to walk all of virtual memory requires architecture specific knowledge. On x86_64, addresses must be sign extended from bit 48, whereas on arm64 the top VA_BITS of address space have their own set of page tables. clear_refs_write() calls walk_page_range() on the range 0 to ~0UL, it provides a test_walk() callback that only expects to be walking over VMAs. Currently walk_pmd_range() will skip memory regions that don't have a VMA, reporting them as a hole. As this call only expects to walk user address space, make it walk 0 to 'highest_vm_end'. Link: http://lkml.kernel.org/r/1472655792-22439-1-git-send-email-james.morse@arm.com Signed-off-by: James Morse Acked-by: Naoya Horiguchi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index f6fa99eca515..d2a70cf2154e 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1070,7 +1070,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, } mmu_notifier_invalidate_range_start(mm, 0, -1); } - walk_page_range(0, ~0UL, &clear_refs_walk); + walk_page_range(0, mm->highest_vm_end, &clear_refs_walk); if (type == CLEAR_REFS_SOFT_DIRTY) mmu_notifier_invalidate_range_end(mm, 0, -1); flush_tlb_mm(mm);