From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (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 2A5852773C3 for ; Thu, 14 May 2026 13:29:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778765349; cv=none; b=ABirwmuWob+rRk3k1WkcSjx34XGUr9rRCaI3pjsqr60Jrvm0AC1Msy8tTg2E8QjtwODrMEC3yzSHK1NWk0zIBKF/PXYmOQAvY2Rk+Pf95xvGO4+c8uDnIGo9svm7ZwKxMfp1AUA4i5zeC70GfkwNe7Rw8tN/DSTJ+0o8r5KBXWo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778765349; c=relaxed/simple; bh=/htvruVWym1bQsi8fQdburgDbXqcQpRYNNGCNxuN6Vs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=feHzGHgvkmrB2MYlZq30vsMjZ5Iwvy+FwU7Op7FpUD408aCCWCARBLofhnkdRorr0X6Rnohuje5XtIEYa8uoswPCtZErAMUnpuYSZB1xHzRte6HyF2SE8Nm0fLiFMLjuruU8v3ubY0WSCD4aYniCIaVb8VeF6nSYDGBuDhX6kZs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Gy4rLQF3; arc=none smtp.client-ip=95.215.58.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Gy4rLQF3" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1778765333; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CHsQvgnGni5VzgHRfyddSYqk4CVVONQEgEqMCt8cdnY=; b=Gy4rLQF3LbRi2vNN5nxzWcmxA0rj1izyKV4hVle7D6TZWBOFHaO+fDNE1T6lfPxCtV+ZWm C6dXs4GRA6SUMk/uccaOIKQE0nAtepkm5OPEDqz31U98o9qMsRRc0r5+v4EDmY4BHXN5K9 jXcavJKzAVTla4wEJjC++MsqneecnGs= From: Lance Yang To: leitao@debian.org Cc: linmiaohe@huawei.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org, nao.horiguchi@gmail.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, corbet@lwn.net, skhan@linuxfoundation.org, liam@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-trace-kernel@vger.kernel.org, kernel-team@meta.com, Lance Yang Subject: Re: [PATCH v7 2/6] mm/memory-failure: surface unhandlable kernel pages as -ENOTRECOVERABLE Date: Thu, 14 May 2026 21:28:30 +0800 Message-Id: <20260514132830.25622-1-lance.yang@linux.dev> In-Reply-To: <20260513-ecc_panic-v7-2-be2e578e61da@debian.org> References: <20260513-ecc_panic-v7-2-be2e578e61da@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On Wed, May 13, 2026 at 08:39:33AM -0700, Breno Leitao wrote: >get_any_page() collapses three different failure modes into a single >-EIO return: > > * the put_page race in the !count_increased path; > * the HWPoisonHandlable() rejection that bounces out of > __get_hwpoison_page() with -EBUSY and exhausts shake_page() retries; > * the HWPoisonHandlable() rejection that goes through the > count_increased / put_page / shake_page retry loop. > >The first is transient (the page is racing with the allocator). The >second can be either transient (a userspace folio briefly off LRU >during migration/compaction) or stable (slab/vmalloc/page-table/ >kernel-stack pages). The third describes a stable kernel-owned page >that the count_increased=true caller already held a reference on. > >Distinguish them on the return path: keep -EIO for both the put_page >race and the -EBUSY-after-retries branch (shake_page() cannot drag a >folio back from active migration, so we cannot prove the page is >permanently kernel-owned from there), keep -EBUSY for the allocation >race (unchanged), and return -ENOTRECOVERABLE only from the >count_increased-true HWPoisonHandlable() rejection that exhausts its >retries -- the caller's reference is structural evidence that the >page is owned by the kernel. > >Extend the unhandlable-page pr_err() to fire for either errno and >update the get_hwpoison_page() kerneldoc. > >memory_failure() still folds every negative return into >MF_MSG_GET_HWPOISON via its existing "else if (res < 0)" branch, so >this patch is a no-op for users of memory_failure() and only changes >the errno that soft_offline_page() can propagate to its callers. A >follow-up wires the new return code through memory_failure() and >reports MF_MSG_KERNEL for the unrecoverable cases. > >Suggested-by: David Hildenbrand >Signed-off-by: Breno Leitao >--- > mm/memory-failure.c | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > >diff --git a/mm/memory-failure.c b/mm/memory-failure.c >index 49bcfbd04d213..bae883df3ccb2 100644 >--- a/mm/memory-failure.c >+++ b/mm/memory-failure.c >@@ -1408,6 +1408,15 @@ static int get_any_page(struct page *p, unsigned long flags) > shake_page(p); > goto try_again; > } >+ /* >+ * Return -EIO rather than -ENOTRECOVERABLE: this >+ * branch is also reached for pages that are merely >+ * off-LRU transiently (e.g. a folio in the middle >+ * of migration or compaction), which shake_page() >+ * cannot drag back. The caller cannot prove the >+ * page is permanently kernel-owned from here, so >+ * keep it on the recoverable errno. >+ */ > ret = -EIO; > goto out; > } >@@ -1427,10 +1436,10 @@ static int get_any_page(struct page *p, unsigned long flags) > goto try_again; > } > put_page(p); >- ret = -EIO; >+ ret = -ENOTRECOVERABLE; > } > out: >- if (ret == -EIO) >+ if (ret == -EIO || ret == -ENOTRECOVERABLE) > pr_err("%#lx: unhandlable page.\n", page_to_pfn(p)); > > return ret; >@@ -1487,7 +1496,10 @@ static int __get_unpoison_page(struct page *page) > * -EIO for pages on which we can not handle memory errors, > * -EBUSY when get_hwpoison_page() has raced with page lifecycle > * operations like allocation and free, >- * -EHWPOISON when the page is hwpoisoned and taken off from buddy. >+ * -EHWPOISON when the page is hwpoisoned and taken off from buddy, >+ * -ENOTRECOVERABLE for stable kernel-owned pages the handler >+ * cannot recover (PG_reserved, slab, vmalloc, page tables, >+ * kernel stacks, and similar non-LRU/non-buddy pages). Did you test this patch series? I don't see how we ever get to -ENOTRECOVERABLE there ... Even with MF_COUNT_INCREASED, the first pass does: if (flags & MF_COUNT_INCREASED) count_increased = true; [...] if (PageHuge(p) || HWPoisonHandlable(p, flags)) { ret = 1; } else { if (pass++ < GET_PAGE_MAX_RETRY_NUM) { <- put_page(p); shake_page(p); count_increased = false; goto try_again; <- } put_page(p); ret = -ENOTRECOVERABLE; } Then we come back with count_increased=false: try_again: if (!count_increased) { ret = __get_hwpoison_page(p, flags); <- if (!ret) { [...] } else if (ret == -EBUSY) { <- [...] ret = -EIO; goto out; <- } } For slab/vmalloc/page-table pages, __get_hwpoison_page() returns -EBUSY: if (!HWPoisonHandlable(&folio->page, flags)) return -EBUSY; so they still seem to end up as -EIO ... Am I missing something? > */ > static int get_hwpoison_page(struct page *p, unsigned long flags) > { > >-- >2.53.0-Meta > >