The patch titled
Subject: mm/debug_vm_pgtable: clear page table entries at destroy_args()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-debug_vm_pgtable-clear-page-table-entries-at-destroy_args.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
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: "Herton R. Krzesinski" <herton(a)redhat.com>
Subject: mm/debug_vm_pgtable: clear page table entries at destroy_args()
Date: Thu, 31 Jul 2025 18:40:51 -0300
The mm/debug_vm_pagetable test allocates manually page table entries for
the tests it runs, using also its manually allocated mm_struct. That in
itself is ok, but when it exits, at destroy_args() it fails to clear those
entries with the *_clear functions.
The problem is that leaves stale entries. If another process allocates an
mm_struct with a pgd at the same address, it may end up running into the
stale entry. This is happening in practice on a debug kernel with
CONFIG_DEBUG_VM_PGTABLE=y, for example this is the output with some extra
debugging I added (it prints a warning trace if pgtables_bytes goes
negative, in addition to the warning at check_mm() function):
[ 2.539353] debug_vm_pgtable: [get_random_vaddr ]: random_vaddr is 0x7ea247140000
[ 2.539366] kmem_cache info
[ 2.539374] kmem_cachep 0x000000002ce82385 - freelist 0x0000000000000000 - offset 0x508
[ 2.539447] debug_vm_pgtable: [init_args ]: args->mm is 0x000000002267cc9e
(...)
[ 2.552800] WARNING: CPU: 5 PID: 116 at include/linux/mm.h:2841 free_pud_range+0x8bc/0x8d0
[ 2.552816] Modules linked in:
[ 2.552843] CPU: 5 UID: 0 PID: 116 Comm: modprobe Not tainted 6.12.0-105.debug_vm2.el10.ppc64le+debug #1 VOLUNTARY
[ 2.552859] Hardware name: IBM,9009-41A POWER9 (architected) 0x4e0202 0xf000005 of:IBM,FW910.00 (VL910_062) hv:phyp pSeries
[ 2.552872] NIP: c0000000007eef3c LR: c0000000007eef30 CTR: c0000000003d8c90
[ 2.552885] REGS: c0000000622e73b0 TRAP: 0700 Not tainted (6.12.0-105.debug_vm2.el10.ppc64le+debug)
[ 2.552899] MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24002822 XER: 0000000a
[ 2.552954] CFAR: c0000000008f03f0 IRQMASK: 0
[ 2.552954] GPR00: c0000000007eef30 c0000000622e7650 c000000002b1ac00 0000000000000001
[ 2.552954] GPR04: 0000000000000008 0000000000000000 c0000000007eef30 ffffffffffffffff
[ 2.552954] GPR08: 00000000ffff00f5 0000000000000001 0000000000000048 0000000000004000
[ 2.552954] GPR12: 00000003fa440000 c000000017ffa300 c0000000051d9f80 ffffffffffffffdb
[ 2.552954] GPR16: 0000000000000000 0000000000000008 000000000000000a 60000000000000e0
[ 2.552954] GPR20: 4080000000000000 c0000000113af038 00007fffcf130000 0000700000000000
[ 2.552954] GPR24: c000000062a6a000 0000000000000001 8000000062a68000 0000000000000001
[ 2.552954] GPR28: 000000000000000a c000000062ebc600 0000000000002000 c000000062ebc760
[ 2.553170] NIP [c0000000007eef3c] free_pud_range+0x8bc/0x8d0
[ 2.553185] LR [c0000000007eef30] free_pud_range+0x8b0/0x8d0
[ 2.553199] Call Trace:
[ 2.553207] [c0000000622e7650] [c0000000007eef30] free_pud_range+0x8b0/0x8d0 (unreliable)
[ 2.553229] [c0000000622e7750] [c0000000007f40b4] free_pgd_range+0x284/0x3b0
[ 2.553248] [c0000000622e7800] [c0000000007f4630] free_pgtables+0x450/0x570
[ 2.553274] [c0000000622e78e0] [c0000000008161c0] exit_mmap+0x250/0x650
[ 2.553292] [c0000000622e7a30] [c0000000001b95b8] __mmput+0x98/0x290
[ 2.558344] [c0000000622e7a80] [c0000000001d1018] exit_mm+0x118/0x1b0
[ 2.558361] [c0000000622e7ac0] [c0000000001d141c] do_exit+0x2ec/0x870
[ 2.558376] [c0000000622e7b60] [c0000000001d1ca8] do_group_exit+0x88/0x150
[ 2.558391] [c0000000622e7bb0] [c0000000001d1db8] sys_exit_group+0x48/0x50
[ 2.558407] [c0000000622e7be0] [c00000000003d810] system_call_exception+0x1e0/0x4c0
[ 2.558423] [c0000000622e7e50] [c00000000000d05c] system_call_vectored_common+0x15c/0x2ec
(...)
[ 2.558892] ---[ end trace 0000000000000000 ]---
[ 2.559022] BUG: Bad rss-counter state mm:000000002267cc9e type:MM_ANONPAGES val:1
[ 2.559037] BUG: non-zero pgtables_bytes on freeing mm: -6144
Here the modprobe process ended up with an allocated mm_struct from the
mm_struct slab that was used before by the debug_vm_pgtable test. That is
not a problem, since the mm_struct is initialized again etc., however, if
it ends up using the same pgd table, it bumps into the old stale entry
when clearing/freeing the page table entries, so it tries to free an entry
already gone (that one which was allocated by the debug_vm_pgtable test),
which also explains the negative pgtables_bytes since it's accounting for
not allocated entries in the current process.
As far as I looked pgd_{alloc,free} etc. does not clear entries, and
clearing of the entries is explicitly done in the free_pgtables->
free_pgd_range->free_p4d_range->free_pud_range->free_pmd_range->
free_pte_range path. However, the debug_vm_pgtable test does not call
free_pgtables, since it allocates mm_struct and entries manually for its
test and eg. not goes through page faults. So it also should clear
manually the entries before exit at destroy_args().
This problem was noticed on a reboot X number of times test being done on
a powerpc host, with a debug kernel with CONFIG_DEBUG_VM_PGTABLE enabled.
Depends on the system, but on a 100 times reboot loop the problem could
manifest once or twice, if a process ends up getting the right mm->pgd
entry with the stale entries used by mm/debug_vm_pagetable. After using
this patch, I couldn't reproduce/experience the problems anymore. I was
able to reproduce the problem as well on latest upstream kernel (6.16).
I also modified destroy_args() to use mmput() instead of mmdrop(), there
is no reason to hold mm_users reference and not release the mm_struct
entirely, and in the output above with my debugging prints I already had
patched it to use mmput, it did not fix the problem, but helped in the
debugging as well.
Link: https://lkml.kernel.org/r/20250731214051.4115182-1-herton@redhat.com
Fixes: 3c9b84f044a9e ("mm/debug_vm_pgtable: introduce struct pgtable_debug_args")
Signed-off-by: Herton R. Krzesinski <herton(a)redhat.com>
Cc: Anshuman Khandual <anshuman.khandual(a)arm.com>
Cc: Christophe Leroy <christophe.leroy(a)csgroup.eu>
Cc: Gavin Shan <gshan(a)redhat.com>
Cc: Gerald Schaefer <gerald.schaefer(a)linux.ibm.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/debug_vm_pgtable.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/mm/debug_vm_pgtable.c~mm-debug_vm_pgtable-clear-page-table-entries-at-destroy_args
+++ a/mm/debug_vm_pgtable.c
@@ -1041,29 +1041,34 @@ static void __init destroy_args(struct p
/* Free page table entries */
if (args->start_ptep) {
+ pmd_clear(args->pmdp);
pte_free(args->mm, args->start_ptep);
mm_dec_nr_ptes(args->mm);
}
if (args->start_pmdp) {
+ pud_clear(args->pudp);
pmd_free(args->mm, args->start_pmdp);
mm_dec_nr_pmds(args->mm);
}
if (args->start_pudp) {
+ p4d_clear(args->p4dp);
pud_free(args->mm, args->start_pudp);
mm_dec_nr_puds(args->mm);
}
- if (args->start_p4dp)
+ if (args->start_p4dp) {
+ pgd_clear(args->pgdp);
p4d_free(args->mm, args->start_p4dp);
+ }
/* Free vma and mm struct */
if (args->vma)
vm_area_free(args->vma);
if (args->mm)
- mmdrop(args->mm);
+ mmput(args->mm);
}
static struct page * __init
_
Patches currently in -mm which might be from herton(a)redhat.com are
mm-debug_vm_pgtable-clear-page-table-entries-at-destroy_args.patch
To prevent timing attacks, HMAC value comparison needs to be constant
time. Replace the memcmp() with the correct function, crypto_memneq().
Fixes: 1085b8276bb4 ("tpm: Add the rest of the session HMAC API")
Cc: stable(a)vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers(a)kernel.org>
---
drivers/char/tpm/Kconfig | 1 +
drivers/char/tpm/tpm2-sessions.c | 6 +++---
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index dddd702b2454a..f9d8a4e966867 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -31,10 +31,11 @@ config TCG_TPM2_HMAC
bool "Use HMAC and encrypted transactions on the TPM bus"
default X86_64
select CRYPTO_ECDH
select CRYPTO_LIB_AESCFB
select CRYPTO_LIB_SHA256
+ select CRYPTO_LIB_UTILS
help
Setting this causes us to deploy a scheme which uses request
and response HMACs in addition to encryption for
communicating with the TPM to prevent or detect bus snooping
and interposer attacks (see tpm-security.rst). Saying Y
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index bdb119453dfbe..5fbd62ee50903 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -69,10 +69,11 @@
#include <linux/unaligned.h>
#include <crypto/kpp.h>
#include <crypto/ecdh.h>
#include <crypto/hash.h>
#include <crypto/hmac.h>
+#include <crypto/utils.h>
/* maximum number of names the TPM must remember for authorization */
#define AUTH_MAX_NAMES 3
#define AES_KEY_BYTES AES_KEYSIZE_128
@@ -827,16 +828,15 @@ int tpm_buf_check_hmac_response(struct tpm_chip *chip, struct tpm_buf *buf,
sha256_update(&sctx, auth->our_nonce, sizeof(auth->our_nonce));
sha256_update(&sctx, &auth->attrs, 1);
/* we're done with the rphash, so put our idea of the hmac there */
tpm2_hmac_final(&sctx, auth->session_key, sizeof(auth->session_key)
+ auth->passphrase_len, rphash);
- if (memcmp(rphash, &buf->data[offset_s], SHA256_DIGEST_SIZE) == 0) {
- rc = 0;
- } else {
+ if (crypto_memneq(rphash, &buf->data[offset_s], SHA256_DIGEST_SIZE)) {
dev_err(&chip->dev, "TPM: HMAC check failed\n");
goto out;
}
+ rc = 0;
/* now do response decryption */
if (auth->attrs & TPM2_SA_ENCRYPT) {
/* need key and IV */
tpm2_KDFa(auth->session_key, SHA256_DIGEST_SIZE
--
2.50.1
The patch titled
Subject: kunit: kasan_test: disable fortify string checker on kasan_strings() test
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
kunit-kasan_test-disable-fortify-string-checker-on-kasan_strings-test.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
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: Yeoreum Yun <yeoreum.yun(a)arm.com>
Subject: kunit: kasan_test: disable fortify string checker on kasan_strings() test
Date: Fri, 1 Aug 2025 13:02:36 +0100
Similar to commit 09c6304e38e4 ("kasan: test: fix compatibility with
FORTIFY_SOURCE") the kernel is panicing in kasan_string().
This is due to the `src` and `ptr` not being hidden from the optimizer
which would disable the runtime fortify string checker.
Call trace:
__fortify_panic+0x10/0x20 (P)
kasan_strings+0x980/0x9b0
kunit_try_run_case+0x68/0x190
kunit_generic_run_threadfn_adapter+0x34/0x68
kthread+0x1c4/0x228
ret_from_fork+0x10/0x20
Code: d503233f a9bf7bfd 910003fd 9424b243 (d4210000)
---[ end trace 0000000000000000 ]---
note: kunit_try_catch[128] exited with irqs disabled
note: kunit_try_catch[128] exited with preempt_count 1
# kasan_strings: try faulted: last
** replaying previous printk message **
# kasan_strings: try faulted: last line seen mm/kasan/kasan_test_c.c:1600
# kasan_strings: internal error occurred preventing test case from running: -4
Link: https://lkml.kernel.org/r/20250801120236.2962642-1-yeoreum.yun@arm.com
Fixes: 73228c7ecc5e ("KASAN: port KASAN Tests to KUnit")
Signed-off-by: Yeoreum Yun <yeoreum.yun(a)arm.com>
Cc: Alexander Potapenko <glider(a)google.com>
Cc: Andrey Konovalov <andreyknvl(a)gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a(a)gmail.com>
Cc: Dmitriy Vyukov <dvyukov(a)google.com>
Cc: Vincenzo Frascino <vincenzo.frascino(a)arm.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/kasan/kasan_test_c.c | 2 ++
1 file changed, 2 insertions(+)
--- a/mm/kasan/kasan_test_c.c~kunit-kasan_test-disable-fortify-string-checker-on-kasan_strings-test
+++ a/mm/kasan/kasan_test_c.c
@@ -1578,9 +1578,11 @@ static void kasan_strings(struct kunit *
ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+ OPTIMIZER_HIDE_VAR(ptr);
src = kmalloc(KASAN_GRANULE_SIZE, GFP_KERNEL | __GFP_ZERO);
strscpy(src, "f0cacc1a0000000", KASAN_GRANULE_SIZE);
+ OPTIMIZER_HIDE_VAR(src);
/*
* Make sure that strscpy() does not trigger KASAN if it overreads into
_
Patches currently in -mm which might be from yeoreum.yun(a)arm.com are
kunit-kasan_test-disable-fortify-string-checker-on-kasan_strings-test.patch
The commit in the Fixes tag breaks my laptop (found by git bisect).
My home RJ45 LAN cable cannot connect after that commit.
The call to netif_carrier_on() should be done when netif_carrier_ok()
is false. Not when it's true. Because calling netif_carrier_on() when
__LINK_STATE_NOCARRIER is not set actually does nothing.
Cc: Armando Budianto <sprite(a)gnuweeb.org>
Cc: stable(a)vger.kernel.org
Closes: https://lore.kernel.org/netdev/0752dee6-43d6-4e1f-81d2-4248142cccd2@gnuweeb…
Fixes: 0d9cfc9b8cb1 ("net: usbnet: Avoid potential RCU stall on LINK_CHANGE event")
Signed-off-by: Ammar Faizi <ammarfaizi2(a)gnuweeb.org>
---
drivers/net/usb/usbnet.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index bc1d8631ffe0..1eb98eeb64f9 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1107,31 +1107,31 @@ static const struct ethtool_ops usbnet_ethtool_ops = {
};
/*-------------------------------------------------------------------------*/
static void __handle_link_change(struct usbnet *dev)
{
if (!test_bit(EVENT_DEV_OPEN, &dev->flags))
return;
if (!netif_carrier_ok(dev->net)) {
+ if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags))
+ netif_carrier_on(dev->net);
+
/* kill URBs for reading packets to save bus bandwidth */
unlink_urbs(dev, &dev->rxq);
/*
* tx_timeout will unlink URBs for sending packets and
* tx queue is stopped by netcore after link becomes off
*/
} else {
- if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags))
- netif_carrier_on(dev->net);
-
/* submitting URBs for reading packets */
tasklet_schedule(&dev->bh);
}
/* hard_mtu or rx_urb_size may change during link change */
usbnet_update_max_qlen(dev);
clear_bit(EVENT_LINK_CHANGE, &dev->flags);
}
--
Ammar Faizi
The Gemalto Cinterion PLS83-W modem (cdc_ether) is emitting confusing link
up and down events when the WWAN interface is activated on the modem-side.
Interrupt URBs will in consecutive polls grab:
* Link Connected
* Link Disconnected
* Link Connected
Where the last Connected is then a stable link state.
When the system is under load this may cause the unlink_urbs() work in
__handle_link_change() to not complete before the next usbnet_link_change()
call turns the carrier on again, allowing rx_submit() to queue new SKBs.
In that event the URB queue is filled faster than it can drain, ending up
in a RCU stall:
rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 0-.... } 33108 jiffies s: 201 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
Call trace:
arch_local_irq_enable+0x4/0x8
local_bh_enable+0x18/0x20
__netdev_alloc_skb+0x18c/0x1cc
rx_submit+0x68/0x1f8 [usbnet]
rx_alloc_submit+0x4c/0x74 [usbnet]
usbnet_bh+0x1d8/0x218 [usbnet]
usbnet_bh_tasklet+0x10/0x18 [usbnet]
tasklet_action_common+0xa8/0x110
tasklet_action+0x2c/0x34
handle_softirqs+0x2cc/0x3a0
__do_softirq+0x10/0x18
____do_softirq+0xc/0x14
call_on_irq_stack+0x24/0x34
do_softirq_own_stack+0x18/0x20
__irq_exit_rcu+0xa8/0xb8
irq_exit_rcu+0xc/0x30
el1_interrupt+0x34/0x48
el1h_64_irq_handler+0x14/0x1c
el1h_64_irq+0x68/0x6c
_raw_spin_unlock_irqrestore+0x38/0x48
xhci_urb_dequeue+0x1ac/0x45c [xhci_hcd]
unlink1+0xd4/0xdc [usbcore]
usb_hcd_unlink_urb+0x70/0xb0 [usbcore]
usb_unlink_urb+0x24/0x44 [usbcore]
unlink_urbs.constprop.0.isra.0+0x64/0xa8 [usbnet]
__handle_link_change+0x34/0x70 [usbnet]
usbnet_deferred_kevent+0x1c0/0x320 [usbnet]
process_scheduled_works+0x2d0/0x48c
worker_thread+0x150/0x1dc
kthread+0xd8/0xe8
ret_from_fork+0x10/0x20
Get around the problem by delaying the carrier on to the scheduled work.
This needs a new flag to keep track of the necessary action.
The carrier ok check cannot be removed as it remains required for the
LINK_RESET event flow.
Fixes: 4b49f58fff00 ("usbnet: handle link change")
Cc: stable(a)vger.kernel.org
Signed-off-by: John Ernberg <john.ernberg(a)actia.se>
---
I've been testing this quite aggressively over a night, and seems equally
stable to my first approach. I'm a little bit concerned that the bit stuff
can now race (although much smaller) in the opposite direction, that a
carrier off can occur between test_and_clear_bit() and the carrier on
action in the handler. Leaving the carrier on when it shouldn't be.
v2:
- target tree in patch description.
- Drop Ming Lei from address list as their address bounces.
- Rework solution based on feedback by Jakub (let me know if you want a
Suggested-by tag, if we're keeping this direction)
v1: https://lore.kernel.org/netdev/20250710085028.1070922-1-john.ernberg@actia.…
Tested on 6.12.20 and forward ported. Stack trace from 6.12.20.
---
drivers/net/usb/usbnet.c | 11 ++++++++---
include/linux/usb/usbnet.h | 1 +
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index c04e715a4c2a..bc1d8631ffe0 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1122,6 +1122,9 @@ static void __handle_link_change(struct usbnet *dev)
* tx queue is stopped by netcore after link becomes off
*/
} else {
+ if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags))
+ netif_carrier_on(dev->net);
+
/* submitting URBs for reading packets */
tasklet_schedule(&dev->bh);
}
@@ -2009,10 +2012,12 @@ EXPORT_SYMBOL(usbnet_manage_power);
void usbnet_link_change(struct usbnet *dev, bool link, bool need_reset)
{
/* update link after link is reseted */
- if (link && !need_reset)
- netif_carrier_on(dev->net);
- else
+ if (link && !need_reset) {
+ set_bit(EVENT_LINK_CARRIER_ON, &dev->flags);
+ } else {
+ clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags);
netif_carrier_off(dev->net);
+ }
if (need_reset && link)
usbnet_defer_kevent(dev, EVENT_LINK_RESET);
diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
index 0b9f1e598e3a..4bc6bb01a0eb 100644
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -76,6 +76,7 @@ struct usbnet {
# define EVENT_LINK_CHANGE 11
# define EVENT_SET_RX_MODE 12
# define EVENT_NO_IP_ALIGN 13
+# define EVENT_LINK_CARRIER_ON 14
/* This one is special, as it indicates that the device is going away
* there are cyclic dependencies between tasklet, timer and bh
* that must be broken
--
2.49.0
Hi,
The issue that I originally fixed with
commit 8ff4fb276e23 ("pinctrl: amd: Clear GPIO debounce for suspend")
I have found out will be a problem on more platforms due to more designs
switching to power button controlled this way.
I think it would be a good idea to take it back to stable kernels.
Thanks!