When page_poison detects page corruption it's useful to see who freed a
page recently to have a guess where write-after-free corruption happens.

After this change corruption report has extra page data.
Example report from real corruption (includes only page_pwner part):

    pagealloc: memory corruption
    e00000014cd61d10: 11 00 00 00 00 00 00 00 30 1d d2 ff ff 0f 00 60  ........0......`
    e00000014cd61d20: b0 1d d2 ff ff 0f 00 60 90 fe 1c 00 08 00 00 20  .......`.......
    ...
    CPU: 1 PID: 220402 Comm: cc1plus Not tainted 5.12.0-rc5-00107-g9720c6f59ecf #245
    Hardware name: hp server rx3600, BIOS 04.03 04/08/2008
    ...
    Call Trace:
     [<a000000100015210>] show_stack+0x90/0xc0
     [<a000000101163390>] dump_stack+0x150/0x1c0
     [<a0000001003f1e90>] __kernel_unpoison_pages+0x410/0x440
     [<a0000001003c2460>] get_page_from_freelist+0x1460/0x2ca0
     [<a0000001003c6be0>] __alloc_pages_nodemask+0x3c0/0x660
     [<a0000001003ed690>] alloc_pages_vma+0xb0/0x500
     [<a00000010037deb0>] __handle_mm_fault+0x1230/0x1fe0
     [<a00000010037ef70>] handle_mm_fault+0x310/0x4e0
     [<a00000010005dc70>] ia64_do_page_fault+0x1f0/0xb80
     [<a00000010000ca00>] ia64_leave_kernel+0x0/0x270
    page_owner tracks the page as freed
    page allocated via order 0, migratetype Movable,
      gfp_mask 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 37, ts 8173444098740
     __reset_page_owner+0x40/0x200
     free_pcp_prepare+0x4d0/0x600
     free_unref_page+0x20/0x1c0
     __put_page+0x110/0x1a0
     migrate_pages+0x16d0/0x1dc0
     compact_zone+0xfc0/0x1aa0
     proactive_compact_node+0xd0/0x1e0
     kcompactd+0x550/0x600
     kthread+0x2c0/0x2e0
     call_payload+0x50/0x80

Here we can see that page was freed by page migration but something
managed to write to it afterwards.

[slyfox@gentoo.org: s/dump_page_owner/dump_page/, per Vlastimil]
  Link: https://lkml.kernel.org/r/20210407230800.1086854-1-slyfox@gentoo.org

Link: https://lkml.kernel.org/r/20210404141735.2152984-1-slyfox@gentoo.orgSigned-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>