diff options
| author | Ryan Roberts <ryan.roberts@arm.com> | 2025-04-22 09:18:15 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2025-05-09 13:43:07 +0100 |
| commit | 61ef8ddaa35e341508d8fa891c33029ed5f75779 (patch) | |
| tree | d1611c186ad51da1e0ca3c279077765f2527d08c /mm/vmalloc.c | |
| parent | f89b399e8d6e9fdef92b15164c2737ac8ef5831a (diff) | |
mm/vmalloc: Warn on improper use of vunmap_range()
A call to vmalloc_huge() may cause memory blocks to be mapped at pmd or
pud level. But it is possible to subsequently call vunmap_range() on a
sub-range of the mapped memory, which partially overlaps a pmd or pud.
In this case, vmalloc unmaps the entire pmd or pud so that the
no-overlapping portion is also unmapped. Clearly that would have a bad
outcome, but it's not something that any callers do today as far as I
can tell. So I guess it's just expected that callers will not do this.
However, it would be useful to know if this happened in future; let's
add a warning to cover the eventuality.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Tested-by: Luiz Capitulino <luizcap@redhat.com>
Link: https://lore.kernel.org/r/20250422081822.1836315-8-ryan.roberts@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'mm/vmalloc.c')
| -rw-r--r-- | mm/vmalloc.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 3ed720a787ec..d60d3a29d149 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -374,8 +374,10 @@ static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, if (cleared || pmd_bad(*pmd)) *mask |= PGTBL_PMD_MODIFIED; - if (cleared) + if (cleared) { + WARN_ON(next - addr < PMD_SIZE); continue; + } if (pmd_none_or_clear_bad(pmd)) continue; vunmap_pte_range(pmd, addr, next, mask); @@ -399,8 +401,10 @@ static void vunmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, if (cleared || pud_bad(*pud)) *mask |= PGTBL_PUD_MODIFIED; - if (cleared) + if (cleared) { + WARN_ON(next - addr < PUD_SIZE); continue; + } if (pud_none_or_clear_bad(pud)) continue; vunmap_pmd_range(pud, addr, next, mask); |