On 2/7/20 8:44 PM, Matthew Wilcox wrote:
...
> - if (PageCompound(page))
> - pr_warn("page:%px refcount:%d mapcount:%d mapping:%px "
> - "index:%#lx compound_mapcount: %d\n",
> - page, page_ref_count(page), mapcount,
> - page->mapping, page_to_pgoff(page),
> - compound_mapcount(page));
> + if (compound)
> + pr_warn("page:%px refcount:%d mapcount:%d mapping:%p "
> + "index:%#lx head:%px order:%u compound_mapcount:%d\n",
> + page, page_ref_count(head), mapcount,
> + mapping, page_to_pgoff(page), head,
> + compound_order(head), compound_mapcount(page));
OK, so the patch now produces the following output for a normal page and a huge page:
page:ffffea0011f68540 refcount:1025 mapcount:1 mapping:00000000b9ef1410 index:0x0
anon flags: 0x17ffe0000080036(referenced|uptodate|lru|active|swapbacked)
raw: 017ffe0000080036 ffffea0011f684c8 ffffea0010eeab88 ffff888495396581
raw: 0000000000000000 0000000000000000 0000040100000000 0000000000000000
page dumped because: test: dump_page()
page:ffffea0010ed2740 refcount:513 mapcount:1 mapping:00000000b9ef1410 index:0xb2 head:ffffea0010ed0000 order:9 compound_mapcount:1
anon flags: 0x17ffe0000000000()
raw: 017ffe0000000000 ffffea0010ed0001 ffffea0010ed2748 dead000000000400
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
head: 017ffe0000090036 ffffea0011ff8ec8 ffffea0010ed8008 ffff888495396581
head: 0000000000000015 0000000000000000 00000201ffffffff 0000000000000000
page dumped because: test: dump_page()
...which is looking very good!
Minor point: How do you and everyone feel about the line length? I do see it getting
pretty long, and I'm about to add the following to it, as a separate patch on top of this:
"compound_pincount:N"
...which just makes it even worse. And on some serial terminals this can get cut
off, so I'm wondering if maybe doing another pr_warn(), and a duplicated page pointer
output, to break up the line would help, like this output:
page:ffffea0010ed2740 refcount:513 mapcount:1 mapping:00000000b9ef1410 index:0xb2 head:ffffea0010ed0000
page:ffffea0010ed2740 order:9 compound_mapcount:1
anon flags: 0x17ffe0000000000()
raw: 017ffe0000000000 ffffea0010ed0001 ffffea0010ed2748 dead000000000400
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
head: 017ffe0000090036 ffffea0011ff8ec8 ffffea0010ed8008 ffff888495396581
head: 0000000000000015 0000000000000000 00000201ffffffff 0000000000000000
page dumped because: test: dump_page()
...which then becomes this, in a future patch:
page:ffffea0010ed2740 refcount:513 mapcount:1 mapping:00000000b9ef1410 index:0xb2 head:ffffea0010ed0000
page:ffffea0010ed2740 order:9 compound_mapcount:1 compound_pincount:1
anon flags: 0x17ffe0000000000()
raw: 017ffe0000000000 ffffea0010ed0001 ffffea0010ed2748 dead000000000400
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
head: 017ffe0000090036 ffffea0011ff8ec8 ffffea0010ed8008 ffff888495396581
head: 0000000000000015 0000000000000000 00000201ffffffff 0000000000000000
page dumped because: test: dump_page()
...or is it best in your experience to leave that line as an "atomic" print statement?
thanks,
--
John Hubbard
NVIDIA
> else
> - pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx\n",
> + pr_warn("page:%px refcount:%d mapcount:%d mapping:%p index:%#lx\n",
> page, page_ref_count(page), mapcount,
> - page->mapping, page_to_pgoff(page));
> + mapping, page_to_pgoff(page));
> if (PageKsm(page))
> type = "ksm ";
> else if (PageAnon(page))
> @@ -106,6 +115,10 @@ void __dump_page(struct page *page, const char *reason)
> print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
> sizeof(unsigned long), page,
> sizeof(struct page), false);
> + if (head != page)
> + print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
> + sizeof(unsigned long), head,
> + sizeof(struct page), false);
>
> if (reason)
> pr_warn("page dumped because: %s\n", reason);
>
