On Mon, Jun 29, 2020 at 03:38:13PM -0700, John Hubbard wrote:
> On 2020-06-29 08:19, Matthew Wilcox (Oracle) wrote:
> > Tail page flags contain very little useful information. Print the head
> > page's flags instead (even though PageHead is a little misleading).
>
> You are right about the tail page. And the raw output provides the tail
> page flags, in case someone *really* needs to dig into tail page problems,
> so that's all good.
>
> However, I just gave this a spin, and seeing the "|head" in the list for
> my "tail page: dump_page test" is also slightly misleading for me, too.
We could also do ...
@@ -48,6 +48,8 @@ void __dump_page(struct page *page, const char *reason)
struct address_space *mapping;
bool page_poisoned = PagePoisoned(page);
bool compound = PageCompound(page);
+ unsigned long flags = page->flags;
+
/*
* Accessing the pageblock without the zone lock. It could change to
* "isolate" again in the meantime, but since we are just dumping the
@@ -165,7 +162,9 @@ void __dump_page(struct page *page, const char *reason)
out_mapping:
BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
- pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
+ if (head != page)
+ flags = head->flags & ~PG_head;
+ pr_warn("%sflags: %#lx(%pGp)%s\n", type, flags, &flags,
page_cma ? " CMA" : "");
hex_only:
