Hi Milan, On Tue, Apr 15, 2025 at 05:01:15PM +0200, Milan Broz wrote: > Hi, > > I tried upstream stable git and bisect, this is the conclusion: > > - upstream 6.1.134 is still broken > > - bisect points to this patch > (Patch cannot be easily reverted, it need some other patches, anyway, it can > be used as reference what need to be backported) > > 476c1dfefab8b98ae9c3e3ad283c2ac10d30c774 is the first bad commit > commit 476c1dfefab8b98ae9c3e3ad283c2ac10d30c774 > Author: David Howells <[email protected]> > Date: Fri May 26 22:41:40 2023 +0100 > > mm: Don't pin ZERO_PAGE in pin_user_pages() > > [ Upstream commit c8070b78751955e59b42457b974bea4a4fe00187 ] > > Make pin_user_pages*() leave a ZERO_PAGE unpinned if it extracts a pointer > to it from the page tables and make unpin_user_page*() correspondingly > ignore a ZERO_PAGE when unpinning. We don't want to risk overrunning a > zero page's refcount as we're only allowed ~2 million pins on it - > something that userspace can conceivably trigger. > > Add a pair of functions to test whether a page or a folio is a ZERO_PAGE. > > Signed-off-by: David Howells <[email protected]> > cc: Christoph Hellwig <[email protected]> > cc: David Hildenbrand <[email protected]> > cc: Lorenzo Stoakes <[email protected]> > cc: Andrew Morton <[email protected]> > cc: Jens Axboe <[email protected]> > cc: Al Viro <[email protected]> > cc: Matthew Wilcox <[email protected]> > cc: Jan Kara <[email protected]> > cc: Jeff Layton <[email protected]> > cc: Jason Gunthorpe <[email protected]> > cc: Logan Gunthorpe <[email protected]> > cc: Hillf Danton <[email protected]> > cc: Christian Brauner <[email protected]> > cc: Linus Torvalds <[email protected]> > cc: [email protected] > cc: [email protected] > cc: [email protected] > cc: [email protected] > Reviewed-by: Lorenzo Stoakes <[email protected]> > Reviewed-by: Christoph Hellwig <[email protected]> > Acked-by: David Hildenbrand <[email protected]> > Link: > https://lore.kernel.org/r/[email protected] > Signed-off-by: Jens Axboe <[email protected]> > Stable-dep-of: bddf10d26e6e ("uprobes: Reject the shared zeropage in > uprobe_write_opcode()") > Signed-off-by: Sasha Levin <[email protected]> > > Documentation/core-api/pin_user_pages.rst | 6 ++++++ > include/linux/mm.h | 26 ++++++++++++++++++++++++-- > mm/gup.c | 31 > ++++++++++++++++++++++++++++++- > 3 files changed, 60 insertions(+), 3 deletions(-) > > If you are going to write a mail to upstream kernel list, please cc me.
Thanks for doing that work, I will forward the bug report now upstream (and sure will include you on CC). Regards, Salvatore
