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David Hildenbrand 97e93367e8 x86/mm/pat: fix VM_PAT handling in COW mappings 
commit 04c35ab3bd upstream.

PAT handling won't do the right thing in COW mappings: the first PTE (or,
in fact, all PTEs) can be replaced during write faults to point at anon
folios.  Reliably recovering the correct PFN and cachemode using
follow_phys() from PTEs will not work in COW mappings.

Using follow_phys(), we might just get the address+protection of the anon
folio (which is very wrong), or fail on swap/nonswap entries, failing
follow_phys() and triggering a WARN_ON_ONCE() in untrack_pfn() and
track_pfn_copy(), not properly calling free_pfn_range().

In free_pfn_range(), we either wouldn't call memtype_free() or would call
it with the wrong range, possibly leaking memory.

To fix that, let's update follow_phys() to refuse returning anon folios,
and fallback to using the stored PFN inside vma->vm_pgoff for COW mappings
if we run into that.

We will now properly handle untrack_pfn() with COW mappings, where we
don't need the cachemode.  We'll have to fail fork()->track_pfn_copy() if
the first page was replaced by an anon folio, though: we'd have to store
the cachemode in the VMA to make this work, likely growing the VMA size.

For now, lets keep it simple and let track_pfn_copy() just fail in that
case: it would have failed in the past with swap/nonswap entries already,
and it would have done the wrong thing with anon folios.

Simple reproducer to trigger the WARN_ON_ONCE() in untrack_pfn():

<--- C reproducer --->
 #include <stdio.h>
 #include <sys/mman.h>
 #include <unistd.h>
 #include <liburing.h>

 int main(void)
 {
         struct io_uring_params p = {};
         int ring_fd;
         size_t size;
         char *map;

         ring_fd = io_uring_setup(1, &p);
         if (ring_fd < 0) {
                 perror("io_uring_setup");
                 return 1;
         }
         size = p.sq_off.array + p.sq_entries * sizeof(unsigned);

         /* Map the submission queue ring MAP_PRIVATE */
         map = mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
                    ring_fd, IORING_OFF_SQ_RING);
         if (map == MAP_FAILED) {
                 perror("mmap");
                 return 1;
         }

         /* We have at least one page. Let's COW it. */
         *map = 0;
         pause();
         return 0;
 }
<--- C reproducer --->

On a system with 16 GiB RAM and swap configured:
 # ./iouring &
 # memhog 16G
 # killall iouring
[  301.552930] ------------[ cut here ]------------
[  301.553285] WARNING: CPU: 7 PID: 1402 at arch/x86/mm/pat/memtype.c:1060 untrack_pfn+0xf4/0x100
[  301.553989] Modules linked in: binfmt_misc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_g
[  301.558232] CPU: 7 PID: 1402 Comm: iouring Not tainted 6.7.5-100.fc38.x86_64 #1
[  301.558772] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebu4
[  301.559569] RIP: 0010:untrack_pfn+0xf4/0x100
[  301.559893] Code: 75 c4 eb cf 48 8b 43 10 8b a8 e8 00 00 00 3b 6b 28 74 b8 48 8b 7b 30 e8 ea 1a f7 000
[  301.561189] RSP: 0018:ffffba2c0377fab8 EFLAGS: 00010282
[  301.561590] RAX: 00000000ffffffea RBX: ffff9208c8ce9cc0 RCX: 000000010455e047
[  301.562105] RDX: 07fffffff0eb1e0a RSI: 0000000000000000 RDI: ffff9208c391d200
[  301.562628] RBP: 0000000000000000 R08: ffffba2c0377fab8 R09: 0000000000000000
[  301.563145] R10: ffff9208d2292d50 R11: 0000000000000002 R12: 00007fea890e0000
[  301.563669] R13: 0000000000000000 R14: ffffba2c0377fc08 R15: 0000000000000000
[  301.564186] FS:  0000000000000000(0000) GS:ffff920c2fbc0000(0000) knlGS:0000000000000000
[  301.564773] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  301.565197] CR2: 00007fea88ee8a20 CR3: 00000001033a8000 CR4: 0000000000750ef0
[  301.565725] PKRU: 55555554
[  301.565944] Call Trace:
[  301.566148]  <TASK>
[  301.566325]  ? untrack_pfn+0xf4/0x100
[  301.566618]  ? __warn+0x81/0x130
[  301.566876]  ? untrack_pfn+0xf4/0x100
[  301.567163]  ? report_bug+0x171/0x1a0
[  301.567466]  ? handle_bug+0x3c/0x80
[  301.567743]  ? exc_invalid_op+0x17/0x70
[  301.568038]  ? asm_exc_invalid_op+0x1a/0x20
[  301.568363]  ? untrack_pfn+0xf4/0x100
[  301.568660]  ? untrack_pfn+0x65/0x100
[  301.568947]  unmap_single_vma+0xa6/0xe0
[  301.569247]  unmap_vmas+0xb5/0x190
[  301.569532]  exit_mmap+0xec/0x340
[  301.569801]  __mmput+0x3e/0x130
[  301.570051]  do_exit+0x305/0xaf0
...

Link: https://lkml.kernel.org/r/20240403212131.929421-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Wupeng Ma <mawupeng1@huawei.com>
Closes: https://lkml.kernel.org/r/20240227122814.3781907-1-mawupeng1@huawei.com
Fixes: b1a86e15dc ("x86, pat: remove the dependency on 'vm_pgoff' in track/untrack pfn vma routines")
Fixes: 5899329b19 ("x86: PAT: implement track/untrack of pfnmap regions for x86 - v3")
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2024-04-10 16:28:33 +02:00
Documentation x86/cpu: Enable STIBP on AMD if Automatic IBRS is enabled 2024-04-03 15:19:54 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch x86/mm/pat: fix VM_PAT handling in COW mappings 2024-04-10 16:28:33 +02:00
block block: Do not force full zone append completion in req_bio_endio() 2024-04-03 15:19:49 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: jitter - fix CRYPTO_JITTERENTROPY help text 2024-03-26 18:20:50 -04:00
drivers of: dynamic: Synchronize of_changeset_destroy() with the devlink removals 2024-04-10 16:28:32 +02:00
fs ksmbd: do not set SMB2_GLOBAL_CAP_ENCRYPTION for SMB 3.1.1 2024-04-10 16:28:32 +02:00
include driver core: Introduce device_link_wait_removal() 2024-04-10 16:28:32 +02:00
init init: open /initrd.image with O_LARGEFILE 2024-04-03 15:19:47 +02:00
io_uring io_uring/net: correctly handle multishot recvmsg retry setup 2024-04-03 15:19:33 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Protect against int overflow for stack access size 2024-04-10 16:28:23 +02:00
lib pci_iounmap(): Fix MMIO mapping leak 2024-04-03 15:19:25 +02:00
mm x86/mm/pat: fix VM_PAT handling in COW mappings 2024-04-10 16:28:33 +02:00
net 9p: Fix read/write debug statements to report server reply 2024-04-10 16:28:30 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:12:28 +01:00
scripts scripts/bpf_doc: Use silent mode when exec make cmd 2024-04-10 16:28:21 +02:00
security landlock: Warn once if a Landlock action is requested while disabled 2024-04-03 15:19:32 +02:00
sound ALSA: hda/realtek: Update Panasonic CF-SZ6 quirk to support headset with microphone 2024-04-10 16:28:32 +02:00
tools selftests: reuseaddr_conflict: add missing new line at the end of the output 2024-04-10 16:28:27 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:19:25 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
…
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
…
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add `.rustfmt.toml` 2022-09-28 09:02:20 +02:00
COPYING
…
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 trace: Relocate event helper files 2024-03-06 14:45:17 +00:00
Makefile Linux 6.1.84 2024-04-03 15:19:55 +02:00
README
…

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.