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t=1793809791; bh=atDiQ1jLywCaP3AyVEImB+gZltQy0V8BagrbxL0rfyY=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=b47bOC/3A0RxnUdzrGef+aXOt5L92xLNPUSE5A24szrut0A3kwfnv5GWFo0Rmw85F 5Tdc/bfgkA1gTlKdM81tunrILY6eokjbGK+/nznxio0+VmOHSS6yWR/K4pch4WGfao X2DC1SLRl6EPej/gADIMREih6WMk3VAUk1SsSnmcGdsSUZUeYeijaW8I5LxE64siT8 WKftT+EeRQuUm7+D6LB06kaL/XBI+8Rm8ri7O6/5letBBW2NOtTNrGUsp40RnchhhW pjkd+4ixoPoxzTj4L9EZ3vouC5W4EmnsmzbuEWe1yrwmAZZnqWDTtJ310ri2gkvA1J g0SZpdQQQjhYg== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH 3/4] mm/cma: reject CMA areas that overlap the kernel image Reply-To: sashiko-reviews@lists.linux.dev To: "Radhey Shyam Pandey" , robh@kernel.org, saravanak@kernel.org, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, m.szyprowski@samsung.com, robin.murphy@arm.com, baoquan.he@linux.dev, pasha.tatashin@soleen.com, pratyush@kernel.org Cc: devicetree@vger.kernel.org, linux-mm@kvack.org, kexec@lists.infradead.org, conor+dt@kernel.org In-Reply-To: <20261103162429.2053989-4-radhey.shyam.pandey@amd.com> References: <20261103162429.2053989-1-radhey.shyam.pandey@amd.com> <20261103162429.2053989-4-radhey.shyam.pandey@amd.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 04 Nov 2026 16:29:50 +0000 X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: B49F4180006 X-Stat-Signature: 4z9pw6iodp9ajyyeko9ea4iytnrgtzkf X-Rspam-User: X-HE-Tag: 1793809792-524760 X-HE-Meta: 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 uCxPOnTf 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [High] mm/cma: __pa_symbol(_text) triggers BUG() on arm32 DEBUG_VIRTUAL -- commit efca63a89d010b4bf63ea1571c8931374f2ec14d Author: Radhey Shyam Pandey mm/cma: reject CMA areas that overlap the kernel image This commit updates cma_init_reserved_mem() to reject CMA regions that overlap the kernel image range [_text, _end) so that cma_activate_area() cannot free kernel image pages into MIGRATE_CMA. > diff --git a/mm/cma.c b/mm/cma.c > index 9c53b2b70dc8f..3231a53161cda 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -31,6 +31,8 @@ > #include > #include > =20 > +#include > + > #include "internal.h" > #include "cma.h" > #include "mm_init.h" > @@ -68,6 +70,16 @@ bool cma_has_dynamic_base(const struct cma *cma) > return test_bit(CMA_DYNAMIC_BASE, &cma->flags); > } > =20 > +static bool cma_overlaps_kernel_image(phys_addr_t base, phys_addr_t size) > +{ > + phys_addr_t end; > + > + if (check_add_overflow(base, size, &end)) > + return true; > + > + return base < __pa_symbol(_end) && __pa_symbol(_text) < end; > +} > + > static unsigned long cma_bitmap_aligned_mask(const struct cma *cma, > unsigned int align_order) > { > @@ -295,6 +307,15 @@ int __init cma_init_reserved_mem(phys_addr_t base, p= hys_addr_t size, > if (!size || !memblock_is_region_reserved(base, size)) > return -EINVAL; > =20 > + if (cma_overlaps_kernel_image(base, size)) { > + phys_addr_t text =3D __pa_symbol(_text); > + phys_addr_t end =3D __pa_symbol(_end); > + > + pr_err("area %s (%pa, size %pa) overlaps kernel image [%pa-%pa]\n", > + name ?: "(unnamed)", &base, &size, &text, &end); > + return -EBUSY; > + } [Severity: High] Is __pa_symbol(_text) safe to call in architecture-independent CMA code? In include/asm-generic/sections.h, _text is noted as architecture-specific: * _text, _data: architecture specific, don't use them in arch-independe= nt code On 32-bit ARM, arch/arm/kernel/vmlinux.lds.S places _text at the start of .head.text before _stext: .head.text : { _text =3D .; HEAD_TEXT } while arch/arm/include/asm/memory.h defines KERNEL_START starting at _stext (or _sdata on CONFIG_XIP_KERNEL): #ifdef CONFIG_XIP_KERNEL #define KERNEL_START _sdata #else #define KERNEL_START _stext #endif #define KERNEL_END _end When CONFIG_DEBUG_VIRTUAL=3Dy is enabled on 32-bit ARM, __pa_symbol(_text) calls __phys_addr_symbol() in arch/arm/mm/physaddr.c: phys_addr_t __phys_addr_symbol(unsigned long x) { /* This is bounds checking against the kernel image only. * __pa_symbol should only be used on kernel symbol addresses. */ VIRTUAL_BUG_ON(x < (unsigned long)KERNEL_START || x > (unsigned long)KERNEL_END); return __pa_symbol_nodebug(x); } Because _text is below KERNEL_START on 32-bit ARM, won't calling cma_init_reserved_mem() -> cma_overlaps_kernel_image() with base < __pa_symbol(_end) trigger VIRTUAL_BUG_ON() during early boot? In addition, on 32-bit ARM with CONFIG_XIP_KERNEL=3Dy (where _text is linked in ROM below PAGE_OFFSET while only [_sdata, _end) is in RAM) and on sparc64 (where [_text, _end) is linked at KERNBASE rather than in the PAGE_OFFSET linear map), won't __pa_symbol(_text) also compute bogus physical addresses for the kernel image? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261103162429.2053= 989-1-radhey.shyam.pandey@amd.com?part=3D3