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: Lorenzo 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: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vma.c b/mm/vma.c
index 0caaeea899a96ce71f79748f6fa2d09bf69f582c..5ef2ea843a8a5e046bb1200ed0739e720cfbc9c3 100644 (file)
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -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;