From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 A1CFF30216D; Thu, 15 Oct 2026 08:16:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792052179; cv=none; b=aZafg+j8dPvIkngwuMYPrHoyXr1O5gPBOK1KzRohR7h61gGSJLKQcHcNfx5X0AcDre2TlpOwHH3FSi2+QXdh5rKL6+l/+rwtw1yfillLDhJ5yCiLwmc9Iar7Xu48sKBh1uRNP7PemY6HCmYKQRWfna6NZzHi0h90UYP/Hakdmko= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792052179; c=relaxed/simple; bh=WQrY/10Sx5ZLKNs4wzxH4x0sne26aGBqwpymsNVEZNo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J3dDNRYWxwQXYejfCejmsJNelMAj2sboDYU+J39tpy5WN+zTtcUCt1ummMPfRftpHTbShR8x4g51yRs34cmqtOEzHO1Jn3edP0dSjdu23R+BalIMLf4Ehg0aFmk2fVzA2BRtZnxQChJhm5PKuIS11aHGcV/uP8oBQfhUJlikX9Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D+2ATOFo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D+2ATOFo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D37BB1F000C4; Thu, 15 Oct 2026 08:16:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792052178; bh=5o7xsZFTTFM2WuI57OlieYgdarxkwcy1AXb2N5U0PlI=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=D+2ATOFoltP2nF981paY8m+3M3kd+Tjj49sknPJQJTqIexCCDVBowBAaT4iXrPvkQ FWqyVyOm+GtBh+CyAbIWI4Vmz7NZHkeBIA+V58wTv/YUKIbdNmh0CRUOSsDKMkGZlp 2Pvze3OMXHOreuqUXKrhGYXUqBQ7PtMqWnrgPqJNrdjehCZJWUGpJq5bEi2xCJYdcf kT3/GHacDQ4CrZrxoFB6qKOPwGvAEqgT4DT5MqKLoqFAMxMEJNf1QG5H/Aq+Guw0bg 4Gv3++dwqzxwhVP4ErsCfK+W6NL8G/MuKPWW3LcOd2pu91diTykdvJZAvyCyTSF3VU RLbvsO4Ql8T7g== Date: Thu, 15 Oct 2026 11:16:11 +0300 From: Mike Rapoport To: Karl Mehltretter Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Luis Chamberlain , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , linux-riscv@lists.infradead.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] riscv: mm: Pre-allocate module page tables for execmem Message-ID: References: <20261015033643.84972-1-kmehltretter@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261015033643.84972-1-kmehltretter@gmail.com> On Thu, Oct 15, 2026 at 05:36:43AM +0200, Karl Mehltretter wrote: > RV64 pre-allocates page-table levels for late kernel mappings. The module > range is guarded by CONFIG_MODULES, although execmem can use it without > modules. > > With CONFIG_BPF_JIT=y and CONFIG_MODULES=n, execmem adds a mapping to > init_mm while the current process retains an empty PGD entry. Initializing > a BPF program pack then faults: > > Unable to handle kernel paging request ... > [ffffffff78000000] pgd=0000000000000000 > ... > bpf_jit_fill_hole_with_zero > bpf_prog_pack_alloc > > Use CONFIG_EXECMEM for the module-range pre-allocation, as powerpc does > for its execmem page-table setup. Both CONFIG_MODULES and CONFIG_BPF_JIT > select it. I think the commit message should mention that BPF_JIT_REGION is inside MODULES region. > Fixes: 2c9e5d4a0082 ("bpf: remove CONFIG_BPF_JIT dependency on CONFIG_MODULES of") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Karl Mehltretter Acked-by: Mike Rapoport (Microsoft) > --- > > Notes: > Tested on a BeagleV Ahead with matched LLVM 18.1.3 builds based on > v7.3-rc7: > > - unpatched: a native XDP attach triggered the Oops above > - patched: native XDP attach and detach completed without an Oops > > arch/riscv/mm/init.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index fb37b0b67efe..d92342c162e2 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -1437,7 +1437,7 @@ static void __init preallocate_pgd_pages_range(unsigned long start, unsigned lon > void __init pgtable_cache_init(void) > { > preallocate_pgd_pages_range(VMALLOC_START, VMALLOC_END, "vmalloc"); > - if (IS_ENABLED(CONFIG_MODULES)) > + if (IS_ENABLED(CONFIG_EXECMEM)) > preallocate_pgd_pages_range(MODULES_VADDR, MODULES_END, "bpf/modules"); > if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) { > preallocate_pgd_pages_range(VMEMMAP_START, VMEMMAP_END, "vmemmap"); > -- > 2.43.0 > -- Sincerely yours, Mike.