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AJvYcCWwP5fNtr3oFERz6yCN7bjs3jFN4p6EUi/dad68JTyC0PeJFL3p5Cb0y9ISL2lwgJnGPfD+YA==@lists.linux.dev X-Gm-Message-State: AOJu0YwezMXQxJ8p6a5J95J7eSDHntQCCUgjljyNMcLhS2sdA6BQhFIj 5QwWTqyR2nnBvuzWMefSREeY1XSCtJLd8de3Ofi6Q3fW9fAEMs/MsJiI62VLr62SsIPhv/LJphy wc4oBmmVOoCP7Cg== X-Received: from wmbd23.prod.google.com ([2002:a05:600c:58d7:b0:477:9654:b44c]) (user=smostafa job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:5285:b0:477:7ab8:aba with SMTP id 5b1f17b1804b1-47ee32e0be0mr36180785e9.1.1768409014935; Wed, 14 Jan 2026 08:43:34 -0800 (PST) Date: Wed, 14 Jan 2026 16:43:22 +0000 In-Reply-To: <20260114164322.787125-1-smostafa@google.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260114164322.787125-1-smostafa@google.com> X-Mailer: git-send-email 2.52.0.457.g6b5491de43-goog Message-ID: <20260114164322.787125-6-smostafa@google.com> Subject: [PATCH v7 5/5] iommu: debug-pagealloc: Check mapped/unmapped kernel memory From: Mostafa Saleh To: linux-mm@kvack.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: corbet@lwn.net, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, xiaqinxin@huawei.com, baolu.lu@linux.intel.com, rdunlap@infradead.org, Mostafa Saleh , Samiullah Khawaja , Pranjal Shrivastava Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Now, as the page_ext holds count of IOMMU mappings, we can use it to assert that any page allocated/freed is indeed not in the IOMMU. The sanitizer doesn=E2=80=99t protect against mapping/unmapping during this period. However, that=E2=80=99s less harmful as the page is not used by the kernel. Reviewed-by: Samiullah Khawaja Reviewed-by: Lu Baolu Reviewed-by: Pranjal Shrivastava Signed-off-by: Mostafa Saleh --- drivers/iommu/iommu-debug-pagealloc.c | 23 +++++++++++++++++++++++ include/linux/iommu-debug-pagealloc.h | 14 ++++++++++++++ include/linux/mm.h | 5 +++++ 3 files changed, 42 insertions(+) diff --git a/drivers/iommu/iommu-debug-pagealloc.c b/drivers/iommu/iommu-de= bug-pagealloc.c index 3ce3385588b2..a283b5dbe26f 100644 --- a/drivers/iommu/iommu-debug-pagealloc.c +++ b/drivers/iommu/iommu-debug-pagealloc.c @@ -9,6 +9,7 @@ #include #include #include +#include =20 #include "iommu-priv.h" =20 @@ -75,6 +76,28 @@ static size_t iommu_debug_page_size(struct iommu_domain = *domain) return 1UL << __ffs(domain->pgsize_bitmap); } =20 +static bool iommu_debug_page_count(const struct page *page) +{ + unsigned int ref; + struct page_ext *page_ext =3D page_ext_get(page); + struct iommu_debug_metadata *d =3D get_iommu_data(page_ext); + + ref =3D atomic_read(&d->ref); + page_ext_put(page_ext); + return ref !=3D 0; +} + +void __iommu_debug_check_unmapped(const struct page *page, int numpages) +{ + while (numpages--) { + if (WARN_ON(iommu_debug_page_count(page))) { + pr_warn("iommu: Detected page leak!\n"); + dump_page_owner(page); + } + page++; + } +} + void __iommu_debug_map(struct iommu_domain *domain, phys_addr_t phys, size= _t size) { size_t off, end; diff --git a/include/linux/iommu-debug-pagealloc.h b/include/linux/iommu-de= bug-pagealloc.h index a439d6815ca1..46c3c1f70150 100644 --- a/include/linux/iommu-debug-pagealloc.h +++ b/include/linux/iommu-debug-pagealloc.h @@ -13,6 +13,20 @@ DECLARE_STATIC_KEY_FALSE(iommu_debug_initialized); =20 extern struct page_ext_operations page_iommu_debug_ops; =20 +void __iommu_debug_check_unmapped(const struct page *page, int numpages); + +static inline void iommu_debug_check_unmapped(const struct page *page, int= numpages) +{ + if (static_branch_unlikely(&iommu_debug_initialized)) + __iommu_debug_check_unmapped(page, numpages); +} + +#else +static inline void iommu_debug_check_unmapped(const struct page *page, + int numpages) +{ +} + #endif /* CONFIG_IOMMU_DEBUG_PAGEALLOC */ =20 #endif /* __LINUX_IOMMU_DEBUG_PAGEALLOC_H */ diff --git a/include/linux/mm.h b/include/linux/mm.h index 6f959d8ca4b4..32205d2a24b2 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -36,6 +36,7 @@ #include #include #include +#include =20 struct mempolicy; struct anon_vma; @@ -4133,12 +4134,16 @@ extern void __kernel_map_pages(struct page *page, i= nt numpages, int enable); #ifdef CONFIG_DEBUG_PAGEALLOC static inline void debug_pagealloc_map_pages(struct page *page, int numpag= es) { + iommu_debug_check_unmapped(page, numpages); + if (debug_pagealloc_enabled_static()) __kernel_map_pages(page, numpages, 1); } =20 static inline void debug_pagealloc_unmap_pages(struct page *page, int nump= ages) { + iommu_debug_check_unmapped(page, numpages); + if (debug_pagealloc_enabled_static()) __kernel_map_pages(page, numpages, 0); } --=20 2.52.0.457.g6b5491de43-goog