The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x cdd0f118ef87db8a664fb5ea366fd1766d2df1cd
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2026010524-anthem-unpainted-c766@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From cdd0f118ef87db8a664fb5ea366fd1766d2df1cd Mon Sep 17 00:00:00 2001
From: Haoxiang Li <haoxiang_li2024(a)163.com>
Date: Mon, 15 Sep 2025 20:09:38 +0800
Subject: [PATCH] media: mediatek: vcodec: Fix a reference leak in
mtk_vcodec_fw_vpu_init()
vpu_get_plat_device() increases the reference count of the returned
platform device. However, when devm_kzalloc() fails, the reference
is not released, causing a reference leak.
Fix this by calling put_device() on fw_pdev->dev before returning
on the error path.
Fixes: e25a89f743b1 ("media: mtk-vcodec: potential dereference of null pointer")
Cc: stable(a)vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024(a)163.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno(a)collabora.com>
Reviewed-by: Tzung-Bi Shih <tzungbi(a)kernel.org>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne(a)collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco(a)kernel.org>
diff --git a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
index 223fb2294894..3632037f78f5 100644
--- a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
+++ b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
@@ -119,8 +119,10 @@ struct mtk_vcodec_fw *mtk_vcodec_fw_vpu_init(void *priv, enum mtk_vcodec_fw_use
vpu_wdt_reg_handler(fw_pdev, mtk_vcodec_vpu_reset_enc_handler, priv, rst_id);
fw = devm_kzalloc(&plat_dev->dev, sizeof(*fw), GFP_KERNEL);
- if (!fw)
+ if (!fw) {
+ put_device(&fw_pdev->dev);
return ERR_PTR(-ENOMEM);
+ }
fw->type = VPU;
fw->ops = &mtk_vcodec_vpu_msg;
fw->pdev = fw_pdev;
The patch titled
Subject: mm/page_alloc: prevent pcp corruption with SMP=n
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-page_alloc-prevent-pcp-corruption-with-smp=n.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 various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Vlastimil Babka <vbabka(a)suse.cz>
Subject: mm/page_alloc: prevent pcp corruption with SMP=n
Date: Mon, 05 Jan 2026 16:08:56 +0100
The kernel test robot has reported:
BUG: spinlock trylock failure on UP on CPU#0, kcompactd0/28
lock: 0xffff888807e35ef0, .magic: dead4ead, .owner: kcompactd0/28, .owner_cpu: 0
CPU: 0 UID: 0 PID: 28 Comm: kcompactd0 Not tainted 6.18.0-rc5-00127-ga06157804399 #1 PREEMPT 8cc09ef94dcec767faa911515ce9e609c45db470
Call Trace:
<IRQ>
__dump_stack (lib/dump_stack.c:95)
dump_stack_lvl (lib/dump_stack.c:123)
dump_stack (lib/dump_stack.c:130)
spin_dump (kernel/locking/spinlock_debug.c:71)
do_raw_spin_trylock (kernel/locking/spinlock_debug.c:?)
_raw_spin_trylock (include/linux/spinlock_api_smp.h:89 kernel/locking/spinlock.c:138)
__free_frozen_pages (mm/page_alloc.c:2973)
___free_pages (mm/page_alloc.c:5295)
__free_pages (mm/page_alloc.c:5334)
tlb_remove_table_rcu (include/linux/mm.h:? include/linux/mm.h:3122 include/asm-generic/tlb.h:220 mm/mmu_gather.c:227 mm/mmu_gather.c:290)
? __cfi_tlb_remove_table_rcu (mm/mmu_gather.c:289)
? rcu_core (kernel/rcu/tree.c:?)
rcu_core (include/linux/rcupdate.h:341 kernel/rcu/tree.c:2607 kernel/rcu/tree.c:2861)
rcu_core_si (kernel/rcu/tree.c:2879)
handle_softirqs (arch/x86/include/asm/jump_label.h:36 include/trace/events/irq.h:142 kernel/softirq.c:623)
__irq_exit_rcu (arch/x86/include/asm/jump_label.h:36 kernel/softirq.c:725)
irq_exit_rcu (kernel/softirq.c:741)
sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1052)
</IRQ>
<TASK>
RIP: 0010:_raw_spin_unlock_irqrestore (arch/x86/include/asm/preempt.h:95 include/linux/spinlock_api_smp.h:152 kernel/locking/spinlock.c:194)
free_pcppages_bulk (mm/page_alloc.c:1494)
drain_pages_zone (include/linux/spinlock.h:391 mm/page_alloc.c:2632)
__drain_all_pages (mm/page_alloc.c:2731)
drain_all_pages (mm/page_alloc.c:2747)
kcompactd (mm/compaction.c:3115)
kthread (kernel/kthread.c:465)
? __cfi_kcompactd (mm/compaction.c:3166)
? __cfi_kthread (kernel/kthread.c:412)
ret_from_fork (arch/x86/kernel/process.c:164)
? __cfi_kthread (kernel/kthread.c:412)
ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
</TASK>
Matthew has analyzed the report and identified that in drain_page_zone()
we are in a section protected by spin_lock(&pcp->lock) and then get an
interrupt that attempts spin_trylock() on the same lock. The code is
designed to work this way without disabling IRQs and occasionally fail the
trylock with a fallback. However, the SMP=n spinlock implementation
assumes spin_trylock() will always succeed, and thus it's normally a
no-op. Here the enabled lock debugging catches the problem, but otherwise
it could cause a corruption of the pcp structure.
The problem has been introduced by commit 574907741599 ("mm/page_alloc:
leave IRQs enabled for per-cpu page allocations"). The pcp locking scheme
recognizes the need for disabling IRQs to prevent nesting spin_trylock()
sections on SMP=n, but the need to prevent the nesting in spin_lock() has
not been recognized. Fix it by introducing local wrappers that change the
spin_lock() to spin_lock_iqsave() with SMP=n and use them in all places
that do spin_lock(&pcp->lock).
Link: https://lkml.kernel.org/r/20260105-fix-pcp-up-v1-1-5579662d2071@suse.cz
Fixes: 574907741599 ("mm/page_alloc: leave IRQs enabled for per-cpu page allocations")
Signed-off-by: Vlastimil Babka <vbabka(a)suse.cz>
Reported-by: kernel test robot <oliver.sang(a)intel.com>
Closes: https://lore.kernel.org/oe-lkp/202512101320.e2f2dd6f-lkp@intel.com
Analyzed-by: Matthew Wilcox <willy(a)infradead.org>
Link: https://lore.kernel.org/all/aUW05pyc9nZkvY-1@casper.infradead.org/
Cc: Brendan Jackman <jackmanb(a)google.com>
Cc: Johannes Weiner <hannes(a)cmpxchg.org>
Cc: Mel Gorman <mgorman(a)techsingularity.net>
Cc: Michal Hocko <mhocko(a)suse.com>
Cc: Sebastian Andrzej Siewior <bigeasy(a)linutronix.de>
Cc: Steven Rostedt <rostedt(a)goodmis.org>
Cc: Suren Baghdasaryan <surenb(a)google.com>
Cc: Zi Yan <ziy(a)nvidia.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/page_alloc.c | 45 +++++++++++++++++++++++++++++++++++++--------
1 file changed, 37 insertions(+), 8 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-prevent-pcp-corruption-with-smp=n
+++ a/mm/page_alloc.c
@@ -167,6 +167,31 @@ static inline void __pcp_trylock_noop(un
pcp_trylock_finish(UP_flags); \
})
+/*
+ * With the UP spinlock implementation, when we spin_lock(&pcp->lock) (for i.e.
+ * a potentially remote cpu drain) and get interrupted by an operation that
+ * attempts pcp_spin_trylock(), we can't rely on the trylock failure due to UP
+ * spinlock assumptions making the trylock a no-op. So we have to turn that
+ * spin_lock() to a spin_lock_irqsave(). This works because on UP there are no
+ * remote cpu's so we can only be locking the only existing local one.
+ */
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
+static inline void __flags_noop(unsigned long *flags) { }
+#define spin_lock_maybe_irqsave(lock, flags) \
+({ \
+ __flags_noop(&(flags)); \
+ spin_lock(lock); \
+})
+#define spin_unlock_maybe_irqrestore(lock, flags) \
+({ \
+ spin_unlock(lock); \
+ __flags_noop(&(flags)); \
+})
+#else
+#define spin_lock_maybe_irqsave(lock, flags) spin_lock_irqsave(lock, flags)
+#define spin_unlock_maybe_irqrestore(lock, flags) spin_unlock_irqrestore(lock, flags)
+#endif
+
#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
DEFINE_PER_CPU(int, numa_node);
EXPORT_PER_CPU_SYMBOL(numa_node);
@@ -2556,6 +2581,7 @@ static int rmqueue_bulk(struct zone *zon
bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp)
{
int high_min, to_drain, to_drain_batched, batch;
+ unsigned long UP_flags;
bool todo = false;
high_min = READ_ONCE(pcp->high_min);
@@ -2575,9 +2601,9 @@ bool decay_pcp_high(struct zone *zone, s
to_drain = pcp->count - pcp->high;
while (to_drain > 0) {
to_drain_batched = min(to_drain, batch);
- spin_lock(&pcp->lock);
+ spin_lock_maybe_irqsave(&pcp->lock, UP_flags);
free_pcppages_bulk(zone, to_drain_batched, pcp, 0);
- spin_unlock(&pcp->lock);
+ spin_unlock_maybe_irqrestore(&pcp->lock, UP_flags);
todo = true;
to_drain -= to_drain_batched;
@@ -2594,14 +2620,15 @@ bool decay_pcp_high(struct zone *zone, s
*/
void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
{
+ unsigned long UP_flags;
int to_drain, batch;
batch = READ_ONCE(pcp->batch);
to_drain = min(pcp->count, batch);
if (to_drain > 0) {
- spin_lock(&pcp->lock);
+ spin_lock_maybe_irqsave(&pcp->lock, UP_flags);
free_pcppages_bulk(zone, to_drain, pcp, 0);
- spin_unlock(&pcp->lock);
+ spin_unlock_maybe_irqrestore(&pcp->lock, UP_flags);
}
}
#endif
@@ -2612,10 +2639,11 @@ void drain_zone_pages(struct zone *zone,
static void drain_pages_zone(unsigned int cpu, struct zone *zone)
{
struct per_cpu_pages *pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
+ unsigned long UP_flags;
int count;
do {
- spin_lock(&pcp->lock);
+ spin_lock_maybe_irqsave(&pcp->lock, UP_flags);
count = pcp->count;
if (count) {
int to_drain = min(count,
@@ -2624,7 +2652,7 @@ static void drain_pages_zone(unsigned in
free_pcppages_bulk(zone, to_drain, pcp, 0);
count -= to_drain;
}
- spin_unlock(&pcp->lock);
+ spin_unlock_maybe_irqrestore(&pcp->lock, UP_flags);
} while (count);
}
@@ -6109,6 +6137,7 @@ static void zone_pcp_update_cacheinfo(st
{
struct per_cpu_pages *pcp;
struct cpu_cacheinfo *cci;
+ unsigned long UP_flags;
pcp = per_cpu_ptr(zone->per_cpu_pageset, cpu);
cci = get_cpu_cacheinfo(cpu);
@@ -6119,12 +6148,12 @@ static void zone_pcp_update_cacheinfo(st
* This can reduce zone lock contention without hurting
* cache-hot pages sharing.
*/
- spin_lock(&pcp->lock);
+ spin_lock_maybe_irqsave(&pcp->lock, UP_flags);
if ((cci->per_cpu_data_slice_size >> PAGE_SHIFT) > 3 * pcp->batch)
pcp->flags |= PCPF_FREE_HIGH_BATCH;
else
pcp->flags &= ~PCPF_FREE_HIGH_BATCH;
- spin_unlock(&pcp->lock);
+ spin_unlock_maybe_irqrestore(&pcp->lock, UP_flags);
}
void setup_pcp_cacheinfo(unsigned int cpu)
_
Patches currently in -mm which might be from vbabka(a)suse.cz are
mm-page_alloc-prevent-pcp-corruption-with-smp=n.patch
mm-page_alloc-thp-prevent-reclaim-for-__gfp_thisnode-thp-allocations.patch
__arm_lpae_unmap() returns size_t but was returning -ENOENT (negative
error code) when encountering an unmapped PTE. Since size_t is unsigned,
-ENOENT (typically -2) becomes a huge positive value (0xFFFFFFFFFFFFFFFE
on 64-bit systems).
This corrupted value propagates through the call chain:
__arm_lpae_unmap() returns -ENOENT as size_t
-> arm_lpae_unmap_pages() returns it
-> __iommu_unmap() adds it to iova address
-> iommu_pgsize() triggers BUG_ON due to corrupted iova
This can cause IOVA address overflow in __iommu_unmap() loop and
trigger BUG_ON in iommu_pgsize() from invalid address alignment.
Fix by returning 0 instead of -ENOENT. The WARN_ON already signals
the error condition, and returning 0 (meaning "nothing unmapped")
is the correct semantic for size_t return type. This matches the
behavior of other io-pgtable implementations (io-pgtable-arm-v7s,
io-pgtable-dart) which return 0 on error conditions.
Fixes: 3318f7b5cefb ("iommu/io-pgtable-arm: Add quirk to quiet WARN_ON()")
Cc: stable(a)vger.kernel.org
Signed-off-by: Chaitanya Kulkarni <ckulkarnilinux(a)gmail.com>
---
drivers/iommu/io-pgtable-arm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index e6626004b323..05d63fe92e43 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -637,7 +637,7 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
pte = READ_ONCE(*ptep);
if (!pte) {
WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN));
- return -ENOENT;
+ return 0;
}
/* If the size matches this level, we're in the right place */
--
2.40.0
The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 0ef841113724166c3c484d0e9ae6db1eb5634fde
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2026010535-unmindful-hedge-1198@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 0ef841113724166c3c484d0e9ae6db1eb5634fde Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan(a)kernel.org>
Date: Fri, 17 Oct 2025 07:33:20 +0200
Subject: [PATCH] media: vpif_capture: fix section mismatch
Platform drivers can be probed after their init sections have been
discarded (e.g. on probe deferral or manual rebind through sysfs) so the
probe function must not live in init.
Note that commit ffa1b391c61b ("V4L/DVB: vpif_cap/disp: Removed section
mismatch warning") incorrectly suppressed the modpost warning.
Fixes: ffa1b391c61b ("V4L/DVB: vpif_cap/disp: Removed section mismatch warning")
Fixes: 6ffefff5a9e7 ("V4L/DVB (12906c): V4L : vpif capture driver for DM6467")
Cc: stable(a)vger.kernel.org # 2.6.32
Signed-off-by: Johan Hovold <johan(a)kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco(a)kernel.org>
diff --git a/drivers/media/platform/ti/davinci/vpif_capture.c b/drivers/media/platform/ti/davinci/vpif_capture.c
index d053972888d1..243c6196b024 100644
--- a/drivers/media/platform/ti/davinci/vpif_capture.c
+++ b/drivers/media/platform/ti/davinci/vpif_capture.c
@@ -1600,7 +1600,7 @@ vpif_capture_get_pdata(struct platform_device *pdev,
* This creates device entries by register itself to the V4L2 driver and
* initializes fields of each channel objects
*/
-static __init int vpif_probe(struct platform_device *pdev)
+static int vpif_probe(struct platform_device *pdev)
{
struct vpif_subdev_info *subdevdata;
struct i2c_adapter *i2c_adap;
@@ -1807,7 +1807,7 @@ static int vpif_resume(struct device *dev)
static SIMPLE_DEV_PM_OPS(vpif_pm_ops, vpif_suspend, vpif_resume);
-static __refdata struct platform_driver vpif_driver = {
+static struct platform_driver vpif_driver = {
.driver = {
.name = VPIF_DRIVER_NAME,
.pm = &vpif_pm_ops,
The patch titled
Subject: mm/vma: enforce VMA fork limit on unfaulted,faulted mremap merge too
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-vma-enforce-vma-fork-limit-on-unfaultedfaulted-mremap-merge-too.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 various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Subject: mm/vma: enforce VMA fork limit on unfaulted,faulted mremap merge too
Date: Mon, 5 Jan 2026 20:11:49 +0000
The is_mergeable_anon_vma() function uses vmg->middle as the source VMA.
However when merging a new VMA, this field is NULL.
In all cases except mremap(), the new VMA will either be newly established
and thus lack an anon_vma, or will be an expansion of an existing VMA thus
we do not care about whether VMA is CoW'd or not.
In the case of an mremap(), we can end up in a situation where we can
accidentally allow an unfaulted/faulted merge with a VMA that has been
forked, violating the general rule that we do not permit this for reasons
of anon_vma lock scalability.
Now we have the ability to be aware of the fact we are copying a VMA and
also know which VMA that is, we can explicitly check for this, so do so.
This is pertinent since commit 879bca0a2c4f ("mm/vma: fix incorrectly
disallowed anonymous VMA merges"), as this patch permits unfaulted/faulted
merges that were previously disallowed running afoul of this issue.
While we are here, vma_had_uncowed_parents() is a confusing name, so make
it simple and rename it to vma_is_fork_child().
Link: https://lkml.kernel.org/r/6e2b9b3024ae1220961c8b81d74296d4720eaf2b.17676382…
Fixes: 879bca0a2c4f ("mm/vma: fix incorrectly disallowed anonymous VMA merges")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Cc: David Hildenbrand (Red Hat) <david(a)kernel.org>
Cc: Jann Horn <jannh(a)google.com>
Cc: Jeongjun Park <aha310510(a)gmail.com>
Cc: Liam Howlett <liam.howlett(a)oracle.com>
Cc: Pedro Falcato <pfalcato(a)suse.de>
Cc: Rik van Riel <riel(a)surriel.com>
Cc: Vlastimil Babka <vbabka(a)suse.cz>
Cc: Yeoreum Yun <yeoreum.yun(a)arm.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/vma.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)
--- a/mm/vma.c~mm-vma-enforce-vma-fork-limit-on-unfaultedfaulted-mremap-merge-too
+++ a/mm/vma.c
@@ -67,18 +67,13 @@ struct mmap_state {
.state = VMA_MERGE_START, \
}
-/*
- * If, at any point, the VMA had unCoW'd mappings from parents, it will maintain
- * more than one anon_vma_chain connecting it to more than one anon_vma. A merge
- * would mean a wider range of folios sharing the root anon_vma lock, and thus
- * potential lock contention, we do not wish to encourage merging such that this
- * scales to a problem.
- */
-static bool vma_had_uncowed_parents(struct vm_area_struct *vma)
+/* Was this VMA ever forked from a parent, i.e. maybe contains CoW mappings? */
+static bool vma_is_fork_child(struct vm_area_struct *vma)
{
/*
* The list_is_singular() test is to avoid merging VMA cloned from
- * parents. This can improve scalability caused by anon_vma lock.
+ * parents. This can improve scalability caused by the anon_vma root
+ * lock.
*/
return vma && vma->anon_vma && !list_is_singular(&vma->anon_vma_chain);
}
@@ -115,11 +110,19 @@ static bool is_mergeable_anon_vma(struct
VM_WARN_ON(src && src_anon != src->anon_vma);
/* Case 1 - we will dup_anon_vma() from src into tgt. */
- if (!tgt_anon && src_anon)
- return !vma_had_uncowed_parents(src);
+ if (!tgt_anon && src_anon) {
+ struct vm_area_struct *copied_from = vmg->copied_from;
+
+ if (vma_is_fork_child(src))
+ return false;
+ if (vma_is_fork_child(copied_from))
+ return false;
+
+ return true;
+ }
/* Case 2 - we will simply use tgt's anon_vma. */
if (tgt_anon && !src_anon)
- return !vma_had_uncowed_parents(tgt);
+ return !vma_is_fork_child(tgt);
/* Case 3 - the anon_vma's are already shared. */
return src_anon == tgt_anon;
}
_
Patches currently in -mm which might be from lorenzo.stoakes(a)oracle.com are
mm-vma-fix-anon_vma-uaf-on-mremap-faulted-unfaulted-merge.patch
tools-testing-selftests-add-tests-for-tgt-src-mremap-merges.patch
mm-vma-enforce-vma-fork-limit-on-unfaultedfaulted-mremap-merge-too.patch
tools-testing-selftests-add-forked-un-faulted-vma-merge-tests.patch
The patch titled
Subject: tools/testing/selftests: add tests for !tgt, src mremap() merges
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
tools-testing-selftests-add-tests-for-tgt-src-mremap-merges.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
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------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Subject: tools/testing/selftests: add tests for !tgt, src mremap() merges
Date: Mon, 5 Jan 2026 20:11:48 +0000
Test that mremap()'ing a VMA into a position such that the target VMA on
merge is unfaulted and the source faulted is correctly performed.
We cover 4 cases:
1. Previous VMA unfaulted:
copied -----|
v
|-----------|.............|
| unfaulted |(faulted VMA)|
|-----------|.............|
prev
target = prev, expand prev to cover.
2. Next VMA unfaulted:
copied -----|
v
|.............|-----------|
|(faulted VMA)| unfaulted |
|.............|-----------|
next
target = next, expand next to cover.
3. Both adjacent VMAs unfaulted:
copied -----|
v
|-----------|.............|-----------|
| unfaulted |(faulted VMA)| unfaulted |
|-----------|.............|-----------|
prev next
target = prev, expand prev to cover.
4. prev unfaulted, next faulted:
copied -----|
v
|-----------|.............|-----------|
| unfaulted |(faulted VMA)| faulted |
|-----------|.............|-----------|
prev next
target = prev, expand prev to cover. Essentially equivalent to 3, but
with additional requirement that next's anon_vma is the same as the
copied VMA's.
Each of these are performed with MREMAP_DONTUNMAP set, which will cause a
KASAN assert for UAF or an assert on zero refcount anon_vma if a bug
exists with correctly propagating anon_vma state in each scenario.
Link: https://lkml.kernel.org/r/f903af2930c7c2c6e0948c886b58d0f42d8e8ba3.17676382…
Fixes: 879bca0a2c4f ("mm/vma: fix incorrectly disallowed anonymous VMA merges")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Cc: David Hildenbrand (Red Hat) <david(a)kernel.org>
Cc: Jann Horn <jannh(a)google.com>
Cc: Jeongjun Park <aha310510(a)gmail.com>
Cc: Liam Howlett <liam.howlett(a)oracle.com>
Cc: Pedro Falcato <pfalcato(a)suse.de>
Cc: Rik van Riel <riel(a)surriel.com>
Cc: Vlastimil Babka <vbabka(a)suse.cz>
Cc: Yeoreum Yun <yeoreum.yun(a)arm.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
tools/testing/selftests/mm/merge.c | 232 +++++++++++++++++++++++++++
1 file changed, 232 insertions(+)
--- a/tools/testing/selftests/mm/merge.c~tools-testing-selftests-add-tests-for-tgt-src-mremap-merges
+++ a/tools/testing/selftests/mm/merge.c
@@ -1171,4 +1171,236 @@ TEST_F(merge, mremap_correct_placed_faul
ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 15 * page_size);
}
+TEST_F(merge, mremap_faulted_to_unfaulted_prev)
+{
+ struct procmap_fd *procmap = &self->procmap;
+ unsigned int page_size = self->page_size;
+ char *ptr_a, *ptr_b;
+
+ /*
+ * mremap() such that A and B merge:
+ *
+ * |------------|
+ * | \ |
+ * |-----------| | / |---------|
+ * | unfaulted | v \ | faulted |
+ * |-----------| / |---------|
+ * B \ A
+ */
+
+ /* Map VMA A into place. */
+ ptr_a = mmap(&self->carveout[page_size + 3 * page_size],
+ 3 * page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_a, MAP_FAILED);
+ /* Fault it in. */
+ ptr_a[0] = 'x';
+
+ /*
+ * Now move it out of the way so we can place VMA B in position,
+ * unfaulted.
+ */
+ ptr_a = mremap(ptr_a, 3 * page_size, 3 * page_size,
+ MREMAP_FIXED | MREMAP_MAYMOVE, &self->carveout[20 * page_size]);
+ ASSERT_NE(ptr_a, MAP_FAILED);
+
+ /* Map VMA B into place. */
+ ptr_b = mmap(&self->carveout[page_size], 3 * page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_b, MAP_FAILED);
+
+ /*
+ * Now move VMA A into position with MREMAP_DONTUNMAP to catch incorrect
+ * anon_vma propagation.
+ */
+ ptr_a = mremap(ptr_a, 3 * page_size, 3 * page_size,
+ MREMAP_FIXED | MREMAP_MAYMOVE | MREMAP_DONTUNMAP,
+ &self->carveout[page_size + 3 * page_size]);
+ ASSERT_NE(ptr_a, MAP_FAILED);
+
+ /* The VMAs should have merged. */
+ ASSERT_TRUE(find_vma_procmap(procmap, ptr_b));
+ ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_b);
+ ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_b + 6 * page_size);
+}
+
+TEST_F(merge, mremap_faulted_to_unfaulted_next)
+{
+ struct procmap_fd *procmap = &self->procmap;
+ unsigned int page_size = self->page_size;
+ char *ptr_a, *ptr_b;
+
+ /*
+ * mremap() such that A and B merge:
+ *
+ * |---------------------------|
+ * | \ |
+ * | |-----------| / |---------|
+ * v | unfaulted | \ | faulted |
+ * |-----------| / |---------|
+ * B \ A
+ *
+ * Then unmap VMA A to trigger the bug.
+ */
+
+ /* Map VMA A into place. */
+ ptr_a = mmap(&self->carveout[page_size], 3 * page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_a, MAP_FAILED);
+ /* Fault it in. */
+ ptr_a[0] = 'x';
+
+ /*
+ * Now move it out of the way so we can place VMA B in position,
+ * unfaulted.
+ */
+ ptr_a = mremap(ptr_a, 3 * page_size, 3 * page_size,
+ MREMAP_FIXED | MREMAP_MAYMOVE, &self->carveout[20 * page_size]);
+ ASSERT_NE(ptr_a, MAP_FAILED);
+
+ /* Map VMA B into place. */
+ ptr_b = mmap(&self->carveout[page_size + 3 * page_size], 3 * page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_b, MAP_FAILED);
+
+ /*
+ * Now move VMA A into position with MREMAP_DONTUNMAP to catch incorrect
+ * anon_vma propagation.
+ */
+ ptr_a = mremap(ptr_a, 3 * page_size, 3 * page_size,
+ MREMAP_FIXED | MREMAP_MAYMOVE | MREMAP_DONTUNMAP,
+ &self->carveout[page_size]);
+ ASSERT_NE(ptr_a, MAP_FAILED);
+
+ /* The VMAs should have merged. */
+ ASSERT_TRUE(find_vma_procmap(procmap, ptr_a));
+ ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_a);
+ ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + 6 * page_size);
+}
+
+TEST_F(merge, mremap_faulted_to_unfaulted_prev_unfaulted_next)
+{
+ struct procmap_fd *procmap = &self->procmap;
+ unsigned int page_size = self->page_size;
+ char *ptr_a, *ptr_b, *ptr_c;
+
+ /*
+ * mremap() with MREMAP_DONTUNMAP such that A, B and C merge:
+ *
+ * |---------------------------|
+ * | \ |
+ * |-----------| | |-----------| / |---------|
+ * | unfaulted | v | unfaulted | \ | faulted |
+ * |-----------| |-----------| / |---------|
+ * A C \ B
+ */
+
+ /* Map VMA B into place. */
+ ptr_b = mmap(&self->carveout[page_size + 3 * page_size], 3 * page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_b, MAP_FAILED);
+ /* Fault it in. */
+ ptr_b[0] = 'x';
+
+ /*
+ * Now move it out of the way so we can place VMAs A, C in position,
+ * unfaulted.
+ */
+ ptr_b = mremap(ptr_b, 3 * page_size, 3 * page_size,
+ MREMAP_FIXED | MREMAP_MAYMOVE, &self->carveout[20 * page_size]);
+ ASSERT_NE(ptr_b, MAP_FAILED);
+
+ /* Map VMA A into place. */
+
+ ptr_a = mmap(&self->carveout[page_size], 3 * page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_a, MAP_FAILED);
+
+ /* Map VMA C into place. */
+ ptr_c = mmap(&self->carveout[page_size + 3 * page_size + 3 * page_size],
+ 3 * page_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_c, MAP_FAILED);
+
+ /*
+ * Now move VMA B into position with MREMAP_DONTUNMAP to catch incorrect
+ * anon_vma propagation.
+ */
+ ptr_b = mremap(ptr_b, 3 * page_size, 3 * page_size,
+ MREMAP_FIXED | MREMAP_MAYMOVE | MREMAP_DONTUNMAP,
+ &self->carveout[page_size + 3 * page_size]);
+ ASSERT_NE(ptr_b, MAP_FAILED);
+
+ /* The VMAs should have merged. */
+ ASSERT_TRUE(find_vma_procmap(procmap, ptr_a));
+ ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_a);
+ ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + 9 * page_size);
+}
+
+TEST_F(merge, mremap_faulted_to_unfaulted_prev_faulted_next)
+{
+ struct procmap_fd *procmap = &self->procmap;
+ unsigned int page_size = self->page_size;
+ char *ptr_a, *ptr_b, *ptr_bc;
+
+ /*
+ * mremap() with MREMAP_DONTUNMAP such that A, B and C merge:
+ *
+ * |---------------------------|
+ * | \ |
+ * |-----------| | |-----------| / |---------|
+ * | unfaulted | v | faulted | \ | faulted |
+ * |-----------| |-----------| / |---------|
+ * A C \ B
+ */
+
+ /*
+ * Map VMA B and C into place. We have to map them together so their
+ * anon_vma is the same and the vma->vm_pgoff's are correctly aligned.
+ */
+ ptr_bc = mmap(&self->carveout[page_size + 3 * page_size],
+ 3 * page_size + 3 * page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_bc, MAP_FAILED);
+
+ /* Fault it in. */
+ ptr_bc[0] = 'x';
+
+ /*
+ * Now move VMA B out the way (splitting VMA BC) so we can place VMA A
+ * in position, unfaulted, and leave the remainder of the VMA we just
+ * moved in place, faulted, as VMA C.
+ */
+ ptr_b = mremap(ptr_bc, 3 * page_size, 3 * page_size,
+ MREMAP_FIXED | MREMAP_MAYMOVE, &self->carveout[20 * page_size]);
+ ASSERT_NE(ptr_b, MAP_FAILED);
+
+ /* Map VMA A into place. */
+ ptr_a = mmap(&self->carveout[page_size], 3 * page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+ ASSERT_NE(ptr_a, MAP_FAILED);
+
+ /*
+ * Now move VMA B into position with MREMAP_DONTUNMAP to catch incorrect
+ * anon_vma propagation.
+ */
+ ptr_b = mremap(ptr_b, 3 * page_size, 3 * page_size,
+ MREMAP_FIXED | MREMAP_MAYMOVE | MREMAP_DONTUNMAP,
+ &self->carveout[page_size + 3 * page_size]);
+ ASSERT_NE(ptr_b, MAP_FAILED);
+
+ /* The VMAs should have merged. */
+ ASSERT_TRUE(find_vma_procmap(procmap, ptr_a));
+ ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_a);
+ ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + 9 * page_size);
+}
+
TEST_HARNESS_MAIN
_
Patches currently in -mm which might be from lorenzo.stoakes(a)oracle.com are
mm-vma-fix-anon_vma-uaf-on-mremap-faulted-unfaulted-merge.patch
tools-testing-selftests-add-tests-for-tgt-src-mremap-merges.patch
mm-vma-enforce-vma-fork-limit-on-unfaultedfaulted-mremap-merge-too.patch
tools-testing-selftests-add-forked-un-faulted-vma-merge-tests.patch