From: "Matthew Wilcox (Oracle)" <willy@infradead.org> mainline inclusion from mainline-v6.13-rc2 commit 4de22b2a6a7477d84d9a01eb6b62a9117309d722 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IB9L9C Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ------------------------------------------- It is unsafe to call PageTail() in dump_page() as page_is_fake_head() will almost certainly return true when called on a head page that is copied to the stack. That will cause the VM_BUG_ON_PGFLAGS() in const_folio_flags() to trigger when it shouldn't. Fortunately, we don't need to call PageTail() here; it's fine to have a pointer to a virtual alias of the page's flag word rather than the real page's flag word. Link: https://lkml.kernel.org/r/20241125201721.2963278-1-willy@infradead.org Fixes: fae7d834c43c ("mm: add __dump_folio()") Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Kees Cook <kees@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Conflicts: include/linux/page-flags.h [Conflicts due to ce3467af6bded1c0018ca67ea1599f45fbb8100b isn't merged.] Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- include/linux/page-flags.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 7a67d997eece..6878081cbbc1 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -312,7 +312,7 @@ static unsigned long *folio_flags(struct folio *folio, unsigned n) { struct page *page = &folio->page; - VM_BUG_ON_PGFLAGS(PageTail(page), page); + VM_BUG_ON_PGFLAGS(page->compound_head & 1, page); VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page); return &page[n].flags; } -- 2.34.1