From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F2A0A1DC745 for ; Tue, 3 Sep 2024 20:22:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725394961; cv=none; b=PvOYeoMy8VeZWDEUI/Zq9UuAx+kr1TkoPHm8Ixt0q5BrWW0RfVS0mqmWCxJJdgBgMGOgUIRHmPqtOyht2yUGmkew+pox8Iz5A54Tl1365Nz1sa9uURN37vu6XMGEOgxy7gyPfRIHtQOvzMX+DMftKW0bjQY/xTC0AAPko2UByZ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725394961; c=relaxed/simple; bh=z2q9cdn7Ht19je5yhhchOrKwkMHWod3E1nqnJjVIB6o=; h=Date:To:From:Subject:Message-Id; b=pPhxjHm//CUvpYd/j1rGe9y1T+42ZrLoqEAND5B5vDwtcsFjLoU0ih9aTbtvc/+SLJKu6P4cm+ExaLwZa6rAHvgpUdr85X2SHnOGh+ecDyRnFHzibN4/imAM1yPvEQGxCl96Vi1IuZN8ro0nVd6F1vUnq2Zro1DXd+zKldLDg/w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=EbuRMiom; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="EbuRMiom" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FE02C4CEC4; Tue, 3 Sep 2024 20:22:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1725394960; bh=z2q9cdn7Ht19je5yhhchOrKwkMHWod3E1nqnJjVIB6o=; h=Date:To:From:Subject:From; b=EbuRMiomypp6Kd3a64oUeOfGZxUDgMAGnDDbkIpgj8uKPaB0HEe8dTPp5BZpy59pr /Umy8zdStv7q0kCFXsGNrmTRbgIldN7PGm/TDz86dIK7N/2z/PWdfc0LRfdTh5tJlg TdTxxETnnA7i8Ra5BuRzLnUAOZUuyKSASAikKABc= Date: Tue, 03 Sep 2024 13:22:39 -0700 To: mm-commits@vger.kernel.org,willy@infradead.org,vivek.kasireddy@intel.com,peterx@redhat.com,muchun.song@linux.dev,jgg@nvidia.com,david@redhat.com,steven.sistare@oracle.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-filemap-fix-filemap_get_folios_contig-thp-panic.patch added to mm-hotfixes-unstable branch Message-Id: <20240903202240.6FE02C4CEC4@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/filemap: fix filemap_get_folios_contig THP panic has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-filemap-fix-filemap_get_folios_contig-thp-panic.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-filemap-fix-filemap_get_folios_contig-thp-panic.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Steve Sistare Subject: mm/filemap: fix filemap_get_folios_contig THP panic Date: Tue, 3 Sep 2024 07:25:17 -0700 Patch series "memfd-pin huge page fixes". Fix multiple bugs that occur when using memfd_pin_folios with hugetlb pages and THP. The hugetlb bugs only bite when the page is not yet faulted in when memfd_pin_folios is called. The THP bug bites when the starting offset passed to memfd_pin_folios is not huge page aligned. See the commit messages for details. This patch (of 5): memfd_pin_folios on memory backed by THP panics if the requested start offset is not huge page aligned: BUG: kernel NULL pointer dereference, address: 0000000000000036 RIP: 0010:filemap_get_folios_contig+0xdf/0x290 RSP: 0018:ffffc9002092fbe8 EFLAGS: 00010202 RAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000002 The fault occurs here, because xas_load returns a folio with value 2: filemap_get_folios_contig() for (folio = xas_load(&xas); folio && xas.xa_index <= end; folio = xas_next(&xas)) { ... if (!folio_try_get(folio)) <-- BOOM "2" is an xarray sibling entry. We get it because memfd_pin_folios does not round the indices passed to filemap_get_folios_contig to huge page boundaries for THP, so we load from the middle of a huge page range see a sibling. (It does round for hugetlbfs, at the is_file_hugepages test). To fix, if the folio is a sibling, then return the next index as the starting point for the next call to filemap_get_folios_contig. Link: https://lkml.kernel.org/r/1725373521-451395-1-git-send-email-steven.sistare@oracle.com Link: https://lkml.kernel.org/r/1725373521-451395-2-git-send-email-steven.sistare@oracle.com Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios") Signed-off-by: Steve Sistare Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Matthew Wilcox Cc: Muchun Song Cc: Peter Xu Cc: Vivek Kasireddy Signed-off-by: Andrew Morton --- mm/filemap.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/filemap.c~mm-filemap-fix-filemap_get_folios_contig-thp-panic +++ a/mm/filemap.c @@ -2181,6 +2181,10 @@ unsigned filemap_get_folios_contig(struc if (xa_is_value(folio)) goto update_start; + /* If we landed in the middle of a THP, continue at its end. */ + if (xa_is_sibling(folio)) + goto update_start; + if (!folio_try_get(folio)) goto retry; _ Patches currently in -mm which might be from steven.sistare@oracle.com are mm-filemap-fix-filemap_get_folios_contig-thp-panic.patch mm-hugetlb-fix-memfd_pin_folios-free_huge_pages-leak.patch mm-hugetlb-fix-memfd_pin_folios-resv_huge_pages-leak.patch mm-gup-fix-memfd_pin_folios-hugetlb-page-allocation.patch mm-gup-fix-memfd_pin_folios-alloc-race-panic.patch