From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E8CCFFC1D for ; Sun, 25 May 2025 07:54:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748159661; cv=none; b=Mfl8wIW+u5ZxLw6Wb7G3lY7et1SKmuBpDntV73PIamPVH88Hnzpidni3Wh7vPjLotqKC1EGRepaydvq16MSOCifYa6FkPajwWVBtIjZVxp7N1/exo8ObgfflcTXyfnOq/j00rIxJmmsl9vjZuXGIqBzrdaia1d8OeTbk4f8XJSo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748159661; c=relaxed/simple; bh=rDN519w8Vv69r6m0cXUiWco8al+9qVO9GCZVehowz+c=; h=Date:To:From:Subject:Message-Id; b=VC0/efDjuTVqdb41Ke2XlNYtgnZmu7CF95dZEpS7dXT+daihH147HBBk+5WCM0imK8t/a7Ga7ISAhK4QM83Ykjxyda4Rc1X3Wmxd4EdD7Y81fY1wmujwywjLOKPk+LIY149PXWyF+cHL8YSqMBrhjYcpq7cctwv0LMOTxofdrmU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=1rzN2Hzh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="1rzN2Hzh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8206BC4CEEA; Sun, 25 May 2025 07:54:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1748159660; bh=rDN519w8Vv69r6m0cXUiWco8al+9qVO9GCZVehowz+c=; h=Date:To:From:Subject:From; b=1rzN2Hzh+cbGrU+JGY5+DeeXMlTxHTGhVAhO9faf/4BIwFJsRGB6jeGNrAOBH3JBs /C1g5j6IFzFxF02YkykSIwrv9e6vyf3J43G+iUftLol4ciAJb54CS0UdIjsnsruC0b LgOj186ZTDDUNbxKDdr8DRTxcLsu3PkDNpGIKUWg= Date: Sun, 25 May 2025 00:54:19 -0700 To: mm-commits@vger.kernel.org,ptyadav@amazon.de,osalvador@suse.de,alexghiti@rivosinc.com,rppt@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-cma-make-detection-of-highmem_start-more-robust.patch removed from -mm tree Message-Id: <20250525075420.8206BC4CEEA@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/cma: make detection of highmem_start more robust has been removed from the -mm tree. Its filename was mm-cma-make-detection-of-highmem_start-more-robust.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: "Mike Rapoport (Microsoft)" Subject: mm/cma: make detection of highmem_start more robust Date: Mon, 19 May 2025 20:18:05 +0300 Pratyush Yadav reports the following crash: ------------[ cut here ]------------ kernel BUG at arch/x86/mm/physaddr.c:23! ception 0x06 IP 10:ffffffff812ebbf8 error 0 cr2 0xffff88903ffff000 CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.15.0-rc6+ #231 PREEMPT(undef) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014 RIP: 0010:__phys_addr+0x58/0x60 Code: 01 48 89 c2 48 d3 ea 48 85 d2 75 05 e9 91 52 cf 00 0f 0b 48 3d ff ff ff 1f 77 0f 48 8b 05 20 54 55 01 48 01 d0 e9 78 52 cf 00 <0f> 0b 90 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 0000:ffffffff82803dd8 EFLAGS: 00010006 ORIG_RAX: 0000000000000000 RAX: 000000007fffffff RBX: 00000000ffffffff RCX: 0000000000000000 RDX: 000000007fffffff RSI: 0000000280000000 RDI: ffffffffffffffff RBP: ffffffff82803e68 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff83153180 R11: ffffffff82803e48 R12: ffffffff83c9aed0 R13: 0000000000000000 R14: 0000001040000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:0000000000000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88903ffff000 CR3: 0000000002838000 CR4: 00000000000000b0 Call Trace: ? __cma_declare_contiguous_nid+0x6e/0x340 ? cma_declare_contiguous_nid+0x33/0x70 ? dma_contiguous_reserve_area+0x2f/0x70 ? setup_arch+0x6f1/0x870 ? start_kernel+0x52/0x4b0 ? x86_64_start_reservations+0x29/0x30 ? x86_64_start_kernel+0x7c/0x80 ? common_startup_64+0x13e/0x141 The reason is that __cma_declare_contiguous_nid() does: highmem_start = __pa(high_memory - 1) + 1; If dma_contiguous_reserve_area() (or any other CMA declaration) is called before free_area_init(), high_memory is uninitialized. Without CONFIG_DEBUG_VIRTUAL, it will likely work but use the wrong value for highmem_start. The issue occurs because commit e120d1bc12da ("arch, mm: set high_memory in free_area_init()") moved initialization of high_memory after the call to dma_contiguous_reserve() -> __cma_declare_contiguous_nid() on several architectures. In the case CONFIG_HIGHMEM is enabled, some architectures that actually support HIGHMEM (arm, powerpc and x86) have initialization of high_memory before a possible call to __cma_declare_contiguous_nid() and some initialized high_memory late anyway (arc, csky, microblase, mips, sparc, xtensa) even before the commit e120d1bc12da so they are fine with using uninitialized value of high_memory. And in the case CONFIG_HIGHMEM is disabled high_memory essentially becomes the first address after memory end, so instead of relying on high_memory to calculate highmem_start use memblock_end_of_DRAM() and eliminate the dependency of CMA area creation on high_memory in majority of configurations. Link: https://lkml.kernel.org/r/20250519171805.1288393-1-rppt@kernel.org Fixes: e120d1bc12da ("arch, mm: set high_memory in free_area_init()") Signed-off-by: Mike Rapoport (Microsoft) Reported-by: Pratyush Yadav Tested-by: Pratyush Yadav Tested-by: Alexandre Ghiti Reviewed-by: Oscar Salvador Signed-off-by: Andrew Morton --- mm/cma.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/cma.c~mm-cma-make-detection-of-highmem_start-more-robust +++ a/mm/cma.c @@ -608,7 +608,10 @@ static int __init __cma_declare_contiguo * complain. Find the boundary by adding one to the last valid * address. */ - highmem_start = __pa(high_memory - 1) + 1; + if (IS_ENABLED(CONFIG_HIGHMEM)) + highmem_start = __pa(high_memory - 1) + 1; + else + highmem_start = memblock_end_of_DRAM(); pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n", __func__, &size, &base, &limit, &alignment); _ Patches currently in -mm which might be from rppt@kernel.org are