From 4d45e75a9955ade5c2f49bd96fc4173b2cec9a72 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Thu, 15 Oct 2020 20:13:00 -0700 Subject: mm: remove the now-unnecessary mmget_still_valid() hack The preceding patches have ensured that core dumping properly takes the mmap_lock. Thanks to that, we can now remove mmget_still_valid() and all its users. Signed-off-by: Jann Horn Signed-off-by: Andrew Morton Acked-by: Linus Torvalds Cc: Christoph Hellwig Cc: Alexander Viro Cc: "Eric W . Biederman" Cc: Oleg Nesterov Cc: Hugh Dickins Link: http://lkml.kernel.org/r/20200827114932.3572699-8-jannh@google.com Signed-off-by: Linus Torvalds --- mm/khugepaged.c | 2 +- mm/madvise.c | 17 ----------------- mm/mmap.c | 5 +---- 3 files changed, 2 insertions(+), 22 deletions(-) (limited to 'mm') diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 58b0d9c502a1..4e3dff13eb70 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -434,7 +434,7 @@ static void insert_to_mm_slots_hash(struct mm_struct *mm, static inline int khugepaged_test_exit(struct mm_struct *mm) { - return atomic_read(&mm->mm_users) == 0 || !mmget_still_valid(mm); + return atomic_read(&mm->mm_users) == 0; } static bool hugepage_vma_check(struct vm_area_struct *vma, diff --git a/mm/madvise.c b/mm/madvise.c index 68b761c359d0..fd1f448b4e1d 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1085,23 +1085,6 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) if (write) { if (mmap_write_lock_killable(current->mm)) return -EINTR; - - /* - * We may have stolen the mm from another process - * that is undergoing core dumping. - * - * Right now that's io_ring, in the future it may - * be remote process management and not "current" - * at all. - * - * We need to fix core dumping to not do this, - * but for now we have the mmget_still_valid() - * model. - */ - if (!mmget_still_valid(current->mm)) { - mmap_write_unlock(current->mm); - return -EINTR; - } } else { mmap_read_lock(current->mm); } diff --git a/mm/mmap.c b/mm/mmap.c index 9fb9f8a233c7..ebb92f5515a1 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2562,7 +2562,7 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr) if (vma && (vma->vm_start <= addr)) return vma; /* don't alter vm_end if the coredump is running */ - if (!prev || !mmget_still_valid(mm) || expand_stack(prev, addr)) + if (!prev || expand_stack(prev, addr)) return NULL; if (prev->vm_flags & VM_LOCKED) populate_vma_page_range(prev, addr, prev->vm_end, NULL); @@ -2588,9 +2588,6 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr) return vma; if (!(vma->vm_flags & VM_GROWSDOWN)) return NULL; - /* don't alter vm_start if the coredump is running */ - if (!mmget_still_valid(mm)) - return NULL; start = vma->vm_start; if (expand_stack(vma, addr)) return NULL; -- cgit