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Kun(llfl) b822007e8d device-dax: correct pgoff align in dax_set_mapping() commit `7fcbd9785d` upstream. pgoff should be aligned using ALIGN_DOWN() instead of ALIGN(). Otherwise, vmf->address not aligned to fault_size will be aligned to the next alignment, that can result in memory failure getting the wrong address. It's a subtle situation that only can be observed in page_mapped_in_vma() after the page is page fault handled by dev_dax_huge_fault. Generally, there is little chance to perform page_mapped_in_vma in dev-dax's page unless in specific error injection to the dax device to trigger an MCE - memory-failure. In that case, page_mapped_in_vma() will be triggered to determine which task is accessing the failure address and kill that task in the end. We used self-developed dax device (which is 2M aligned mapping) , to perform error injection to random address. It turned out that error injected to non-2M-aligned address was causing endless MCE until panic. Because page_mapped_in_vma() kept resulting wrong address and the task accessing the failure address was never killed properly: [ 3783.719419] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3784.049006] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3784.049190] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3784.448042] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3784.448186] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3784.792026] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3784.792179] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3785.162502] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3785.162633] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3785.461116] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3785.461247] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3785.764730] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3785.764859] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3786.042128] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3786.042259] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3786.464293] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3786.464423] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3786.818090] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3786.818217] Memory failure: 0x200c9742: recovery action for dax page: Recovered [ 3787.085297] mce: Uncorrected hardware memory error in user-access at 200c9742380 [ 3787.085424] Memory failure: 0x200c9742: recovery action for dax page: Recovered It took us several weeks to pinpoint this problem, but we eventually used bpftrace to trace the page fault and mce address and successfully identified the issue. Joao added: ; Likely we never reproduce in production because we always pin : device-dax regions in the region align they provide (Qemu does : similarly with prealloc in hugetlb/file backed memory). I think this : bug requires that we touch unpinned device-dax regions unaligned to : the device-dax selected alignment (page size i.e. 4K/2M/1G) Link: https://lkml.kernel.org/r/23c02a03e8d666fef11bbe13e85c69c8b4ca0624.1727421694.git.llfl@linux.alibaba.com Fixes: `b9b5777f09` ("device-dax: use ALIGN() for determining pgoff") Signed-off-by: Kun(llfl) <llfl@linux.alibaba.com> Tested-by: JianXiong Zhao <zhaojianxiong.zjx@alibaba-inc.com> Reviewed-by: Joao Martins <joao.m.martins@oracle.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		History 2024-10-17 15:24:36 +02:00
arch	x86/amd_nb: Add new PCI IDs for AMD family 1Ah model 60h	2024-10-17 15:24:22 +02:00
block	blk_iocost: fix more out of bound shifts	2024-10-10 11:57:24 +02:00
certs	certs: Reference revocation list for all keyrings	2023-08-17 20:12:41 +00:00
crypto	crypto: simd - Do not call crypto_alloc_tfm during registration	2024-10-10 11:57:26 +02:00
Documentation	selftests: Introduce Makefile variable to list shared bash scripts	2024-10-17 15:24:13 +02:00
drivers	device-dax: correct pgoff align in dax_set_mapping()	2024-10-17 15:24:36 +02:00
fs	btrfs: zoned: fix missing RCU locking in error message when loading zone info	2024-10-17 15:24:28 +02:00
include	net: Fix an unsafe loop on the list	2024-10-17 15:24:35 +02:00
init	rust: fix the default format for CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT	2024-08-29 17:33:29 +02:00
io_uring	io_uring: check if we need to reschedule during overflow flush	2024-10-17 15:24:18 +02:00
ipc	sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table)	2024-08-11 12:47:13 +02:00
kernel	rcu/nocb: Fix rcuog wake-up from offline softirq	2024-10-17 15:24:30 +02:00
lib	lib/build_OID_registry: avoid non-destructive substitution for Perl < 5.13.2 compat	2024-10-17 15:24:13 +02:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	mm: z3fold: deprecate CONFIG_Z3FOLD	2024-10-10 11:58:02 +02:00
net	mptcp: pm: do not remove closing subflows	2024-10-17 15:24:36 +02:00
rust	rust: sync: require `T: Sync` for `LockedBy::access`	2024-10-10 11:57:44 +02:00
samples	samples/bpf: Fix compilation errors with cf-protection option	2024-10-04 16:29:19 +02:00
scripts	kconfig: qconf: fix buffer overflow in debug links	2024-10-10 11:58:01 +02:00
security	tomoyo: fallback to realpath if symlink's pathname does not exist	2024-10-10 11:57:57 +02:00
sound	PCI: Add function 0 DMA alias quirk for Glenfly Arise chip	2024-10-17 15:24:16 +02:00
tools	selftests: net: no_forwarding: fix VID for $swp2 in one_bridge_two_pvids() test	2024-10-17 15:24:24 +02:00
usr	initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP	2023-06-06 17:54:49 +09:00
virt	KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock	2024-10-04 16:29:47 +02:00
.clang-format	iommu: Add for_each_group_device()	2023-05-23 08:15:51 +02:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore	get_maintainer: add Alan to .get_maintainer.ignore	2022-08-20 15:17:44 -07:00
.gitattributes	.gitattributes: set diff driver for Rust source code files	2023-05-31 17:48:25 +02:00
.gitignore	Remove *.orig pattern from .gitignore	2024-10-04 16:29:44 +02:00
.mailmap	20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues	2023-10-24 09:52:16 -10:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	USB: Remove Wireless USB and UWB documentation	2023-08-09 14:17:32 +02:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	membarrier: riscv: Add full memory barrier in switch_mm()	2024-09-12 11:11:45 +02:00
Makefile	Linux 6.6.56	2024-10-10 12:50:06 +02:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.