From nobody Sat Feb 7 15:22:21 2026 Received: from mail-oa1-f70.google.com (mail-oa1-f70.google.com [209.85.160.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 84A372580CF for ; Tue, 27 Jan 2026 02:35:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.70 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769481322; cv=none; b=u7pI3YF3ugYhUc8RC7iGP8x+GNpYOeC4ReEK9WMbUMjp3S4KjVLG84z8AhE08mGQYmv8v3U06a3FySV7h5qPppfSY9VJKhvHQ4F9OMWyUuSE9KH9j73aNLS1koWAYmr3QfmoToTGyQKKFmya+kz4pYYc0bWF9hAn91GqcAhHWqY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769481322; c=relaxed/simple; bh=n4pakarXYhpu2bCTgkxl4NHM908wL/Jrf+yYk6KL238=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=VmNEx0Gta0F6ek6VO+dpVOeuzdzH1PagCfgZZw1wXzJXg/sIK1N+nqsel6Hkqi6EXz5d/aBQvSoI9RK2/iUJuJxtyWcOjw7NBPEFhwfrJUqT5ChDAFvx05zXIJH51rmRomkkBCxI0PbtGPEwrAFuj4xO+sjStUYDyRsaE8pN+Cs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.160.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oa1-f70.google.com with SMTP id 586e51a60fabf-404201da527so32291021fac.0 for ; Mon, 26 Jan 2026 18:35:21 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769481320; x=1770086120; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=oFj0FIm37ASmuTe4QYk5LYfEu3NgebcEd2sN4JXUYKY=; b=cKQSW3NsyCQ3TKk8QjFiv321+aNyJ0Cs8GDY+1iaWqRheM0Do/BSnOnfl32CZAeJli lsqi26Gzd7Nrn3wSE3LACE5O1bPrhzD/qbIk1aabA6Z2H5U0C57zJUDGtSom6U/QEz14 glqN58G0FD96UHbphmEMsUVFxOvL85OLCvrK8wJ2TL5FuWsf0GjYgaaXnwaB7SQtDYqE 6XUR511lOyGop8QSYY2hazE9yWvv6gdGhP11rE4AZD5sB1Crf+RG01h9m1ugqqd+rY3z XGii6WwXE5yuUYXFdNDiKaPqS7Wooh2lWMF3xjAzqTSWi0gvNHBHXo2qO1Dx4VC4zBoh AwyA== X-Gm-Message-State: AOJu0YzX0yLI9f56QCKhfOYZ4JceFniv9cEuRndK/c4ynQDfpUJDT+ae gjSJKlpzBSFf9z4IhoAX+SL5uIhYqQ0m0xTGs2VyOT9YmAYIDPc6df42R1KhQYIoSm9iI4wURPh I797WcYjx1UvfMht+bFfQExA30lH8KV45kr0w+Me6rXrTrrsaPN2thtAvIHo= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1ca1:b0:65f:a60:606a with SMTP id 006d021491bc7-662f1f6b478mr150587eaf.0.1769481318718; Mon, 26 Jan 2026 18:35:18 -0800 (PST) Date: Mon, 26 Jan 2026 18:35:18 -0800 In-Reply-To: <69780fd2.050a0220.c9109.000a.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69782466.050a0220.c9109.000e.GAE@google.com> Subject: Forwarded: [PATCH] mm: Fix KASAN-induced recursive page faults in ptlock_ptr From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: [PATCH] mm: Fix KASAN-induced recursive page faults in ptlock_ptr Author: kartikey406@gmail.com #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git= master When pte_offset_map_rw_nolock() is called during signal frame setup in the ret_from_fork path, KASAN instrumentation of ptlock_ptr() can trigger recursive page faults. The KASAN shadow memory access itself may cause a page fault while already handling a page fault. In RT priority contexts (SCHED_FIFO), this recursive faulting prevents the task from yielding, causing RCU stalls as the grace period kthread cannot get CPU time. Disable KASAN instrumentation for both variants of ptlock_ptr() to prevent this recursion. Reported-by: syzbot+42836f91edd58eb82c6a@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=3D42836f91edd58eb82c6a Signed-off-by: Deepanshu Kartikey --- include/linux/mm.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index f0d5be9dc736..e4c33731bdd6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3235,7 +3235,7 @@ void __init ptlock_cache_init(void); bool ptlock_alloc(struct ptdesc *ptdesc); void ptlock_free(struct ptdesc *ptdesc); =20 -static inline spinlock_t *ptlock_ptr(struct ptdesc *ptdesc) +static inline spinlock_t *ptlock_ptr(struct ptdesc *ptdesc) __no_sanitize_= address { return ptdesc->ptl; } @@ -3253,7 +3253,7 @@ static inline void ptlock_free(struct ptdesc *ptdesc) { } =20 -static inline spinlock_t *ptlock_ptr(struct ptdesc *ptdesc) +static inline spinlock_t *ptlock_ptr(struct ptdesc *ptdesc) __no_sanitize_= address { return &ptdesc->ptl; } --=20 2.43.0