Hi,
After a stable kernel update, the hwclock command seems no longer
functional on my SPARC system with an ST M48T59Y-70PC1 RTC:
# hwclock
[...long delay...]
hwclock: select() to /dev/rtc0 to wait for clock tick timed out
On prior kernels, there is no problem:
# hwclock
2025-10-22 22:21:04.806992-04:00
I reproduced the same failure on 6.18-rc2 and bisected to this commit:
commit 795cda8338eab036013314dbc0b04aae728880ab
Author: Esben Haabendal <esben(a)geanix.com>
Date: Fri May 16 09:23:35 2025 +0200
rtc: interface: Fix long-standing race when setting alarm
This commit was backported to all current 6.x stable branches,
as well as 5.15.x, so they all have the same regression.
Reverting this commit on top of 6.18-rc2 corrects the problem.
Let me know if you need any more info!
Thanks,
Nick
On a Xen dom0 boot, this feature does not behave, and we end up
calculating:
num_roots = 1
num_nodes = 2
roots_per_node = 0
This causes a divide-by-zero in the modulus inside the loop.
This change adds a couple of guards for invalid states where we might
get a divide-by-zero.
Signed-off-by: Steven Noonan <steven(a)uplinklabs.net>
Signed-off-by: Ariadne Conill <ariadne(a)ariadne.space>
CC: Yazen Ghannam <yazen.ghannam(a)amd.com>
CC: x86(a)vger.kernel.org
CC: stable(a)vger.kernel.org
---
arch/x86/kernel/amd_node.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index 3d0a4768d603c..cdc6ba224d4ad 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -282,6 +282,17 @@ static int __init amd_smn_init(void)
return -ENODEV;
num_nodes = amd_num_nodes();
+
+ if (!num_nodes)
+ return -ENODEV;
+
+ /* Possibly a virtualized environment (e.g. Xen) where we wi
ll get
+ * roots_per_node=0 if the number of roots is fewer than number of
+ * nodes
+ */
+ if (num_roots < num_nodes)
+ return -ENODEV;
+
amd_roots = kcalloc(num_nodes, sizeof(*amd_roots), GFP_KERNEL);
if (!amd_roots)
return -ENOMEM;
--
2.51.2
As reported by Athul upstream in [1], there is a userspace regression caused
by commit 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb
tree") where if there is a bug in a fuse server that causes the server to
never complete writeback, it will make wait_sb_inodes() wait forever, causing
sync paths to hang.
This is a resubmission of this patch [2] that was dropped from the original
series due to a buggy/malicious server still being able to hold up sync() /
the system in other ways if they wanted to, but the wait_sb_inodes() path is
particularly common and easier to hit for malfunctioning servers.
Thanks,
Joanne
[1] https://lore.kernel.org/regressions/CAJnrk1ZjQ8W8NzojsvJPRXiv9TuYPNdj8Ye7=C…
[2] https://lore.kernel.org/linux-fsdevel/20241122232359.429647-4-joannelkoong@…
Joanne Koong (2):
mm: rename AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM to
AS_WRITEBACK_MAY_HANG
fs/writeback: skip inodes with potential writeback hang in
wait_sb_inodes()
fs/fs-writeback.c | 3 +++
fs/fuse/file.c | 2 +-
include/linux/pagemap.h | 10 +++++-----
mm/vmscan.c | 3 +--
4 files changed, 10 insertions(+), 8 deletions(-)
--
2.47.3
The patch titled
Subject: mm/kasan: fix incorrect unpoisoning in vrealloc for KASAN
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-kasan-fix-incorrect-unpoisoning-in-vrealloc-for-kasan.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: Jiayuan Chen <jiayuan.chen(a)linux.dev>
Subject: mm/kasan: fix incorrect unpoisoning in vrealloc for KASAN
Date: Fri, 28 Nov 2025 19:15:14 +0800
Syzkaller reported a memory out-of-bounds bug [1]. This patch fixes two
issues:
1. In vrealloc, we were missing the KASAN_VMALLOC_VM_ALLOC flag when
unpoisoning the extended region. This flag is required to correctly
associate the allocation with KASAN's vmalloc tracking.
Note: In contrast, vzalloc (via __vmalloc_node_range_noprof) explicitly
sets KASAN_VMALLOC_VM_ALLOC and calls kasan_unpoison_vmalloc() with it.
vrealloc must behave consistently ��� especially when reusing existing
vmalloc regions ��� to ensure KASAN can track allocations correctly.
2. When vrealloc reuses an existing vmalloc region (without allocating new
pages), KASAN previously generated a new tag, which broke tag-based
memory access tracking. We now add a 'reuse_tag' parameter to
__kasan_unpoison_vmalloc() to preserve the original tag in such cases.
A new helper kasan_unpoison_vralloc() is introduced to handle this reuse
scenario, ensuring consistent tag behavior during reallocation.
Link: https://lkml.kernel.org/r/20251128111516.244497-1-jiayuan.chen@linux.dev
Link: https://syzkaller.appspot.com/bug?extid=997752115a851cb0cf36 [1]
Fixes: a0309faf1cb0 ("mm: vmalloc: support more granular vrealloc() sizing")
Signed-off-by: Jiayuan Chen <jiayuan.chen(a)linux.dev>
Reported-by: syzbot+997752115a851cb0cf36(a)syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68e243a2.050a0220.1696c6.007d.GAE@google.com/T/
Cc: Alexander Potapenko <glider(a)google.com>
Cc: Andrey Konovalov <andreyknvl(a)gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a(a)gmail.com>
Cc: Danilo Krummrich <dakr(a)kernel.org>
Cc: Dmitriy Vyukov <dvyukov(a)google.com>
Cc: Kees Cook <kees(a)kernel.org>
Cc: "Uladzislau Rezki (Sony)" <urezki(a)gmail.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>
---
include/linux/kasan.h | 21 +++++++++++++++++++--
mm/kasan/hw_tags.c | 4 ++--
mm/kasan/shadow.c | 6 ++++--
mm/vmalloc.c | 4 ++--
4 files changed, 27 insertions(+), 8 deletions(-)
--- a/include/linux/kasan.h~mm-kasan-fix-incorrect-unpoisoning-in-vrealloc-for-kasan
+++ a/include/linux/kasan.h
@@ -596,13 +596,23 @@ static inline void kasan_release_vmalloc
#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
- kasan_vmalloc_flags_t flags);
+ kasan_vmalloc_flags_t flags, bool reuse_tag);
+
+static __always_inline void *kasan_unpoison_vrealloc(const void *start,
+ unsigned long size,
+ kasan_vmalloc_flags_t flags)
+{
+ if (kasan_enabled())
+ return __kasan_unpoison_vmalloc(start, size, flags, true);
+ return (void *)start;
+}
+
static __always_inline void *kasan_unpoison_vmalloc(const void *start,
unsigned long size,
kasan_vmalloc_flags_t flags)
{
if (kasan_enabled())
- return __kasan_unpoison_vmalloc(start, size, flags);
+ return __kasan_unpoison_vmalloc(start, size, flags, false);
return (void *)start;
}
@@ -629,6 +639,13 @@ static inline void kasan_release_vmalloc
unsigned long free_region_end,
unsigned long flags) { }
+static inline void *kasan_unpoison_vrealloc(const void *start,
+ unsigned long size,
+ kasan_vmalloc_flags_t flags)
+{
+ return (void *)start;
+}
+
static inline void *kasan_unpoison_vmalloc(const void *start,
unsigned long size,
kasan_vmalloc_flags_t flags)
--- a/mm/kasan/hw_tags.c~mm-kasan-fix-incorrect-unpoisoning-in-vrealloc-for-kasan
+++ a/mm/kasan/hw_tags.c
@@ -317,7 +317,7 @@ static void init_vmalloc_pages(const voi
}
void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
- kasan_vmalloc_flags_t flags)
+ kasan_vmalloc_flags_t flags, bool reuse_tag)
{
u8 tag;
unsigned long redzone_start, redzone_size;
@@ -361,7 +361,7 @@ void *__kasan_unpoison_vmalloc(const voi
return (void *)start;
}
- tag = kasan_random_tag();
+ tag = reuse_tag ? get_tag(start) : kasan_random_tag();
start = set_tag(start, tag);
/* Unpoison and initialize memory up to size. */
--- a/mm/kasan/shadow.c~mm-kasan-fix-incorrect-unpoisoning-in-vrealloc-for-kasan
+++ a/mm/kasan/shadow.c
@@ -625,7 +625,7 @@ void kasan_release_vmalloc(unsigned long
}
void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
- kasan_vmalloc_flags_t flags)
+ kasan_vmalloc_flags_t flags, bool reuse_tag)
{
/*
* Software KASAN modes unpoison both VM_ALLOC and non-VM_ALLOC
@@ -648,7 +648,9 @@ void *__kasan_unpoison_vmalloc(const voi
!(flags & KASAN_VMALLOC_PROT_NORMAL))
return (void *)start;
- start = set_tag(start, kasan_random_tag());
+ if (!reuse_tag)
+ start = set_tag(start, kasan_random_tag());
+
kasan_unpoison(start, size, false);
return (void *)start;
}
--- a/mm/vmalloc.c~mm-kasan-fix-incorrect-unpoisoning-in-vrealloc-for-kasan
+++ a/mm/vmalloc.c
@@ -4175,8 +4175,8 @@ void *vrealloc_node_align_noprof(const v
* We already have the bytes available in the allocation; use them.
*/
if (size <= alloced_size) {
- kasan_unpoison_vmalloc(p + old_size, size - old_size,
- KASAN_VMALLOC_PROT_NORMAL);
+ kasan_unpoison_vrealloc(p, size,
+ KASAN_VMALLOC_PROT_NORMAL | KASAN_VMALLOC_VM_ALLOC);
/*
* No need to zero memory here, as unused memory will have
* already been zeroed at initial allocation time or during
_
Patches currently in -mm which might be from jiayuan.chen(a)linux.dev are
mm-kasan-fix-incorrect-unpoisoning-in-vrealloc-for-kasan.patch
mm-vmscan-skip-increasing-kswapd_failures-when-reclaim-was-boosted.patch
When fsl_edma_alloc_chan_resources() fails after clk_prepare_enable(),
the error paths only free IRQs and destroy the TCD pool, but forget to
call clk_disable_unprepare(). This causes the channel clock to remain
enabled, leaking power and resources.
Fix it by disabling the channel clock in the error unwind path.
Fixes: d8d4355861d8 ("dmaengine: fsl-edma: add i.MX8ULP edma support")
Cc: stable(a)vger.kernel.org
Suggested-by: Frank Li <Frank.Li(a)nxp.com>
Signed-off-by: Zhen Ni <zhen.ni(a)easystack.cn>
---
Changes in v2:
- Remove FSL_EDMA_DRV_HAS_CHCLK check
Changes in v3:
- Remove cleanup
Changes in v4:
- Re-send as a new thread
---
drivers/dma/fsl-edma-common.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/dma/fsl-edma-common.c b/drivers/dma/fsl-edma-common.c
index 4976d7dde080..11655dcc4d6c 100644
--- a/drivers/dma/fsl-edma-common.c
+++ b/drivers/dma/fsl-edma-common.c
@@ -852,6 +852,7 @@ int fsl_edma_alloc_chan_resources(struct dma_chan *chan)
free_irq(fsl_chan->txirq, fsl_chan);
err_txirq:
dma_pool_destroy(fsl_chan->tcd_pool);
+ clk_disable_unprepare(fsl_chan->clk);
return ret;
}
--
2.20.1