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 9491415B97C for ; Thu, 2 May 2024 15:29:48 +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=1714663788; cv=none; b=d2z9hNiuPzuoQ1PHkJptcqxHWlel4qxrP4bQKTqQn321yQGTGnC4+HfeXwdtPDiZIHo4MNfAoIRflJjtulsouZ3iHMoUrE66Y9tUCe4fIydpJBUhLgcxKTewzw47kg1UzXr4QiesFGh351o7Qj2LsFcw9LroarFoBoSfVJGdsQc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714663788; c=relaxed/simple; bh=pXSG9EW8vHdNbLayuK405giVkOpEpcArWafL1JJAsH0=; h=Date:To:From:Subject:Message-Id; b=u0Lu/TGEBDY+qEiUgGS2xAbtaFt79CitgzwqdvZZea0edMIepugBeB2N5qxPmQ4a3Mr332xEbzO05U5RftRwyH7CXZkHmKMg80N/ZcvwHs8HbDqJ05+zTXBVhb2kc2XMAqYePU3dKyLQFDQ+q7wAUuzTF2bvTurO4MNK53RQGds= 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=0q/At/VD; 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="0q/At/VD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA572C113CC; Thu, 2 May 2024 15:29:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1714663788; bh=pXSG9EW8vHdNbLayuK405giVkOpEpcArWafL1JJAsH0=; h=Date:To:From:Subject:From; b=0q/At/VDDBNkqNkGeNQ14FbWbbPb5dPEhiWNWvLl8vDXODpLP28uJhixVBYtSsGf9 /Ta0LgaQ5ArfWEEjvoO08Cktve4gaW/aBLAnU9NlqIfn0hSaGzwvp1x1R3QfJEm351 hBBuQ/e0IF+WiiJT8YoR9OtKKJQXaR6j6eseugZA= Date: Thu, 02 May 2024 08:29:46 -0700 To: mm-commits@vger.kernel.org,nao.horiguchi@gmail.com,linmiaohe@huawei.com,jane.chu@oracle.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-memory-failure-try-to-send-sigbus-even-if-unmap-failed.patch added to mm-unstable branch Message-Id: <20240502152947.DA572C113CC@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/memory-failure: try to send SIGBUS even if unmap failed has been added to the -mm mm-unstable branch. Its filename is mm-memory-failure-try-to-send-sigbus-even-if-unmap-failed.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-failure-try-to-send-sigbus-even-if-unmap-failed.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Jane Chu Subject: mm/memory-failure: try to send SIGBUS even if unmap failed Date: Wed, 1 May 2024 17:24:56 -0600 Patch series "Enhance soft hwpoison handling and injection". This series aim at the following enhancement - 1. Let one hwpoison injector, that is, madvise(MADV_HWPOISON) to behave more like as if a real UE occurred. Because the other two injectors such as hwpoison-inject and the 'einj' on x86 can't, and it seems to me we need a better simulation to real UE scenario. 2. For years, if the kernel is unable to unmap a hwpoisoned page, it send a SIGKILL instead of SIGBUS to prevent user process from potentially accessing the page again. But in doing so, the user process also lose important information: vaddr, for recovery. Fortunately, the kernel already has code to kill process re-accessing a hwpoisoned page, so remove the '!unmap_success' check. 3. Right now, if a thp page under GUP longterm pin is hwpoisoned, and kernel cannot split the thp page, memory-failure simply ignores the UE and returns. That's not ideal, it could deliver a SIGBUS with useful information for userspace recovery. This patch (of 3): For years when it comes down to kill a process due to hwpoison, a SIGBUS is delivered only if unmap has been successful. Otherwise, a SIGKILL is delivered. And the reason for that is to prevent the involved process from accessing the hwpoisoned page again. Since then a lot has changed, a hwpoisoned page is marked and upon being re-accessed, the process will be killed immediately. So let's take out the '!unmap_success' factor and try to deliver SIGBUS if possible. Link: https://lkml.kernel.org/r/20240501232458.3919593-1-jane.chu@oracle.com Link: https://lkml.kernel.org/r/20240501232458.3919593-2-jane.chu@oracle.com Signed-off-by: Jane Chu Cc: Miaohe Lin Cc: Naoya Horiguchi Signed-off-by: Andrew Morton --- mm/memory-failure.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) --- a/mm/memory-failure.c~mm-memory-failure-try-to-send-sigbus-even-if-unmap-failed +++ a/mm/memory-failure.c @@ -517,19 +517,14 @@ void add_to_kill_ksm(struct task_struct * Also when FAIL is set do a force kill because something went * wrong earlier. */ -static void kill_procs(struct list_head *to_kill, int forcekill, bool fail, +static void kill_procs(struct list_head *to_kill, int forcekill, unsigned long pfn, int flags) { struct to_kill *tk, *next; list_for_each_entry_safe(tk, next, to_kill, nd) { if (forcekill) { - /* - * In case something went wrong with munmapping - * make sure the process doesn't catch the - * signal and then access the memory. Just kill it. - */ - if (fail || tk->addr == -EFAULT) { + if (tk->addr == -EFAULT) { pr_err("%#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n", pfn, tk->tsk->comm, tk->tsk->pid); do_send_sig_info(SIGKILL, SEND_SIG_PRIV, @@ -1660,7 +1655,7 @@ static bool hwpoison_user_mappings(struc */ forcekill = folio_test_dirty(folio) || (flags & MF_MUST_KILL) || !unmap_success; - kill_procs(&tokill, forcekill, !unmap_success, pfn, flags); + kill_procs(&tokill, forcekill, pfn, flags); return unmap_success; } @@ -1724,7 +1719,7 @@ static void unmap_and_kill(struct list_h unmap_mapping_range(mapping, start, size, 0); } - kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags); + kill_procs(to_kill, flags & MF_MUST_KILL, pfn, flags); } /* _ Patches currently in -mm which might be from jane.chu@oracle.com are mm-memory-failure-try-to-send-sigbus-even-if-unmap-failed.patch mm-madvise-add-mf_action_required-to-madvisemadv_hwpoison.patch mm-memory-failure-send-sigbus-in-the-event-of-thp-split-fail.patch