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On 32-bit= , a >> pointer to an allocated xen_page_foreign is stored; on 64-bit, >> xen_page_foreign is stored inline. Checking page->private !=3D NULL is e= nough >> to tell whether a xen_page_foreign needs to be freed on 32-bit and >> page->private is zeroed unconditionally on 64-bit. >>=20 >> It prepares for a future commit that remove PG_private. >>=20 >> No functional change intended. >>=20 >> Assisted-by: Claude:claude-opus-4-8 >> Assisted-by: Codex:gpt-5 >> Signed-off-by: Zi Yan >> To: Juergen Gross >> To: Stefano Stabellini >> Cc: Oleksandr Tyshchenko >> Cc: xen-devel@lists.xenproject.org >> Cc: linux-kernel@vger.kernel.org >> --- >> drivers/xen/balloon.c | 5 +++++ >> drivers/xen/grant-table.c | 11 +++++------ >> 2 files changed, 10 insertions(+), 6 deletions(-) >>=20 >> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c >> index e7f74ea7cd5eb..fdb18348cfdfe 100644 >> --- a/drivers/xen/balloon.c >> +++ b/drivers/xen/balloon.c >> @@ -182,6 +182,11 @@ static struct page *balloon_retrieve(bool require_l= owmem) >> =20 >> __ClearPageOffline(page); >> dec_node_page_state(page, NR_BALLOON_PAGES); >> + /* >> + * clear page->private before giving it out, since it might be used to >> + * store xen_page_foreign info. >> + */ >> + set_page_private(page, 0); > > Who would have set it to !=3D 0 in the first place? No one else, except > > e.g., gnttab_free_pages() resets it to 0 now before calling > xen_free_unpopulated_pages(). After reading more, I agree with you that the above change is unnecesary and will remove it in the next version. Thanks. --=20 Best Regards, Yan, Zi