From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 DD29035F19D; Wed, 26 Aug 2026 10:03:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787738604; cv=none; b=cZ48MinSKVDSXmfCIsTO9Z/4hxKRb7tETOZQ36oPIccB59ycHd0tCGJxCn9dwOrDkdQCf9OAiVBKgAQtGOb/U3v47W+xx0f9NwvdZIu6D+iUTFMLIFrJOUui1d/bshrkCX2vwFV6ZNjcHAewSjlPvut5QfOi5ahmek8BKFbKDqg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787738604; c=relaxed/simple; bh=jiqHUks1m0JXbpeFcnNwxpziXVJoP1qjEoguu8lM/WI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Z89lVykZfln89tjqQIe8UzaLBJbaTaApYP2a2xXJOUfhIgJyNB0Zz5gStcH+alQURfqfF1jGN9FctGqnIxMRo0Hg4IafyewrvoRo1LCChnXEmokAe7kbX4Aq5gm0VJsnEAbrlg4a8Ir7PuN6GHFs8+83/jhqBr7pg99iSSMyVEQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=egVz/zbA; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="egVz/zbA" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=WZakOKFiw1qwrXHhV0NoUSm3EeQmFpLc6hHbXxKxp4w=; b=egVz/zbAaKyEoDL6mec9PlJmKR S0HI06OfojIuS8q55yHaRp10zVsWuRnv4NJ47AgFAr3Jgc5e5I3lUd40o2I2x5+/3vKWCk5vfjnRC W8i/C9kFrAf2hYc6LGqfGt9Q/+Ewe0drS5bnywL83w2+OCBBxNz4ZSnJXiF92vt4xpcoTAcDbCW3F 5vd09+38/5qaBqM4HI10/7+GHQWx63vnOKSj7cZncpze94BPHo04cPQUhcthyFOtCR9q4tUlkoWEX 9j7Ox0ORjD0W04UDwlWrL//J4a7uSkhDAUEpFHOSQ74mtl2viIOkRlUMZ/4h2SMyY3MTrNxdM6x7o LPnA17Fw==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wzATY-00F8SY-28; Wed, 26 Aug 2026 10:03:20 +0000 Date: Wed, 26 Aug 2026 03:03:17 -0700 From: Breno Leitao To: Alexei Starovoitov Cc: sashiko-reviews@lists.linux.dev, bpf Subject: Re: [PATCH] bpf: arena: reschedule while freeing the arena pages Message-ID: References: <20260824-b4-bpf-arena-free-resched-v1-1-5c447477a64b@debian.org> <20260824170831.33E051F000E9@smtp.kernel.org> 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: X-Debian-User: leitao Hello Alexei, On Tue, Aug 25, 2026 at 09:35:03AM -0700, Alexei Starovoitov wrote: > Just to be clear.. Is this needed to backport to some older kernel? > New kernel with CONFIG_PREEMPT_LAZY=y shouldn't need > this old practice of sprinkling cond_resched(). Yes, this is happening on our Meta kernel, and it is crashing a lot on old kernel in production. It does crash a lot for us: 56780 crashes over 1538 hosts in the last 30 days, 41% of all our kernel crashes in that window. But it stops dead at 6.13: 6.11.1 26060 crashes / 160 hosts 6.13.2 26014 crashes / 1119 hosts Looking further, it seems that commit 517e8a7835e8c ("bpf: Fix softlockup in arena_map_free on 64k page kernel") is what is what makes the difference, which landed in v6.14. Meta's arm64 kernels use 64k pages, so before that commit GUARD_SZ / 2 is 32768 and bpf_arena_get_kern_vm_start() is not page aligned So there is nothing to fix upstream, and nothing to fix in the teardown loop. We just need 517e8a7835e8c in our 6.11 and 6.13 branches. Sorry for the noise Thanks, -- pw-bot: rejected