Commit fe1679ed authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Andrew Morton
Browse files

mm/debug: prefer VM_WARN_ON_VMG() to report VMG debug warnings 

Now we have VM_WARN_ON_VMG() to provide us with considerably more debug
output when a debug assert fails, utilise it everywhere we can.

This allows us to have considerably more information to go on when things
go wrong, especially when a non-repro issue occurs as reported by
syzkaller or the like.

Link: https://lkml.kernel.org/r/986e45e9549e71284ac7a7fa878688568a94d58b.1735932169.git.lorenzo.stoakes@oracle.com


Signed-off-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b0d66d82

mm/vma.c

+17 −16
Original line number Diff line number Diff line
@@ -729,19 +729,20 @@ static __must_check struct vm_area_struct *vma_merge_existing_range( 
	bool expanded;



	mmap_assert_write_locked(vmg->mm);

	VM_WARN_ON(!vma); /* We are modifying a VMA, so caller must specify. */

	VM_WARN_ON(vmg->next); /* We set this. */

	VM_WARN_ON(prev && start <= prev->vm_start);

	VM_WARN_ON(start >= end);

	VM_WARN_ON_VMG(!vma, vmg); /* We are modifying a VMA, so caller must specify. */

	VM_WARN_ON_VMG(vmg->next, vmg); /* We set this. */

	VM_WARN_ON_VMG(prev && start <= prev->vm_start, vmg);

	VM_WARN_ON_VMG(start >= end, vmg);



	/*

	 * If vma == prev, then we are offset into a VMA. Otherwise, if we are

	 * not, we must span a portion of the VMA.

	 */

	VM_WARN_ON(vma && ((vma != prev && vmg->start != vma->vm_start) ||

			   vmg->end > vma->vm_end));

	VM_WARN_ON_VMG(vma && ((vma != prev && vmg->start != vma->vm_start) ||

			       vmg->end > vma->vm_end), vmg);

	/* The vmi must be positioned within vmg->vma. */

	VM_WARN_ON(vma && !(vma_iter_addr(vmg->vmi) >= vma->vm_start &&

			    vma_iter_addr(vmg->vmi) < vma->vm_end));

	VM_WARN_ON_VMG(vma && !(vma_iter_addr(vmg->vmi) >= vma->vm_start &&

				vma_iter_addr(vmg->vmi) < vma->vm_end), vmg);



	vmg->state = VMA_MERGE_NOMERGE;
@@ -858,9 +859,9 @@ static __must_check struct vm_area_struct *vma_merge_existing_range( 


		pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start);



		VM_WARN_ON(!merge_right);

		VM_WARN_ON_VMG(!merge_right, vmg);

		/* If we are offset into a VMA, then prev must be vma. */

		VM_WARN_ON(vmg->start > vma->vm_start && prev && vma != prev);

		VM_WARN_ON_VMG(vmg->start > vma->vm_start && prev && vma != prev, vmg);



		if (merge_will_delete_vma) {

			vmg->vma = next;
@@ -972,9 +973,9 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) 
	bool just_expand = vmg->merge_flags & VMG_FLAG_JUST_EXPAND;



	mmap_assert_write_locked(vmg->mm);

	VM_WARN_ON(vmg->vma);

	VM_WARN_ON_VMG(vmg->vma, vmg);

	/* vmi must point at or before the gap. */

	VM_WARN_ON(vma_iter_addr(vmg->vmi) > end);

	VM_WARN_ON_VMG(vma_iter_addr(vmg->vmi) > end, vmg);



	vmg->state = VMA_MERGE_NOMERGE;
@@ -1056,7 +1057,7 @@ int vma_expand(struct vma_merge_struct *vmg) 


		remove_next = true;

		/* This should already have been checked by this point. */

		VM_WARN_ON(!can_merge_remove_vma(next));

		VM_WARN_ON_VMG(!can_merge_remove_vma(next), vmg);

		vma_start_write(next);

		ret = dup_anon_vma(vma, next, &anon_dup);

		if (ret)
@@ -1064,10 +1065,10 @@ int vma_expand(struct vma_merge_struct *vmg) 
	}



	/* Not merging but overwriting any part of next is not handled. */

	VM_WARN_ON(next && !remove_next &&

		  next != vma && vmg->end > next->vm_start);

	VM_WARN_ON_VMG(next && !remove_next &&

		       next != vma && vmg->end > next->vm_start, vmg);

	/* Only handles expanding */

	VM_WARN_ON(vma->vm_start < vmg->start || vma->vm_end > vmg->end);

	VM_WARN_ON_VMG(vma->vm_start < vmg->start || vma->vm_end > vmg->end, vmg);



	if (commit_merge(vmg, NULL, remove_next ? next : NULL, NULL, 0, true))

		goto nomem;