From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794063644; b=p9+eOAyYcAb4D7LP6IVOu+23mCuJSjq/6IQBtRhNUzMZcZhz+xRLcuUEy+3oQVz3SxQP QqljKEfSY066blZh5pYVlCtevaUxjsTCeFaNOegV7tJHdcJJ2uH8umyeqdSD7l0EjcNLa 8peHCIV21JDkXE6P4vhv4BlEpFi8wi+Oxejz5Urz443+CFFEwHVoLIkqLMwN1o/97SHUx HlcUsaxN9Ef2geskM1tnn5AKjhhMGxnCIQYeQ4zTIBRkKCw1dMQEIZHaajk3Mz/xRDORm jc7yHhu1JlKZzmxYDf4jgHEC9vMcx57x42hgWwNeM8INdu4N6+pUeF5kjXERwheYvOw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794063644; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=CCQ6S+4hREmvuZiKc+i5FCqZys23bljPSIWJa0zXRoc=; b=xbK900SHtJPHFdeXOu0aGguyJsDm0ozpQFxSxtnHWoL3wxfvvKUHS5vD3sFBEmCe0awk N3G060rwLxCCOUUAk/EZG7+FGW59g/HtM4O/gIzRFES6iprPlPp+1aFUu0HtT26RodIw0 u9pJOukkshz5W7LpS9D+O6XX8rhWhDK8LmcnmRvtYPg0lNsTdSc9l9y8e7dn6OOqsRifJ 8HCUiKlGSC/WZp6N3TsNmvoTwmcirRCBqccMOXrOTidgk8LC4lZbg+grXOLZSAdr19QI5 3kxtQAWVNFutsgbv07WO22iy9rDIukYfHq01JfEPTrKYbf3W7okivX10fhm3SrRB4Vw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=cPFKhKze; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CBB846082BEF; Sat, 7 Nov 2026 15:00:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=cPFKhKze Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8012B1F0089F; Sat, 7 Nov 2026 15:00:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794063643; bh=CCQ6S+4hREmvuZiKc+i5FCqZys23bljPSIWJa0zXRoc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=cPFKhKzedPulQl7xSvlY3oEWBOtNDgi7w9cVts904x5zBbTj6KqQdTL2uMXUBLhtp qmi0/cRG5g15mEO7ccnwwHiKwiNQTdauiPbTpnfQS57fhbQWNJXzLJyEPFdXaPQ6sM VTrFH1IRqAZL3ouwNFeNTjFlt+TE87UhtIkwjaGU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Gregory Price (Meta)" , Andrew Morton , Joshua Hahn , David Hildenbrand , Zi Yan , Rakie Kim , Ying Huang , Pasha Tatashin , Michal Hocko , Sasha Levin Subject: [PATCH 6.18 758/869] mm/mempolicy: apply bind policies against the scoped allocation zone Date: Sat, 7 Nov 2026 08:57:20 -0500 Message-ID: <20261107134918.415627815@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134852.069646174@linuxfoundation.org> References: <20261107134852.069646174@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gregory Price (Meta) [ Upstream commit d4ea410ce4b8aa46a316476ea2624a357bf31fa9 ] QEMU fails to start a guest with a VFIO device when guest RAM comes from a memory backend bound to a movable-only node: vfio_container_dma_map(0x55b1b1317800, 0x0, 0x10000000, 0x7f39a2200000) = -12 (Cannot allocate memory) VFIO pins guest RAM when the device is realized, and the pin faults the pages in. io_uring fixed buffers fail the same way. Faulting the range in before pinning lets the same pin succeed, since resident pages are migrated off the node instead. A long-term pin faults under memalloc_pin_save(). PF_MEMALLOC_PIN makes current_gfp_context() clear __GFP_MOVABLE, but policy_nodemask() tests apply_policy_zone() against the caller's gfp. The bind keeps its movable-only nodemask, and the allocation finds no usable zone: page allocation failure: order:0, mode:0x140dc2(GFP_HIGHUSER|__GFP_ZERO|__GFP_COMP), nodemask=1,cpuset=/,mems_allowed=0-1 Call Trace: warn_alloc+0x136/0x150 __alloc_frozen_pages_noprof+0xed8/0x1720 alloc_pages_mpol+0xaa/0x170 vma_alloc_folio_noprof+0x65/0xd0 __handle_mm_fault+0x137b/0x1ac0 handle_mm_fault+0xa0/0x270 __get_user_pages+0x250/0xfd0 __gup_longterm_locked+0x116/0x870 gup_fast_fallback+0xcfc/0xdf0 pin_user_pages_fast+0x47/0x60 io_pin_pages+0x9a/0x110 Base page faults fail with -ENOMEM. hugetlb faults fail with -EFAULT. Check the policy zone against current_gfp_context(gfp), so a pin-scoped fault falls back off the movable-only nodemask, like any other non-movable allocation under the same bind. Tested in qemu with a dax/kmem movable-only node 1. io_uring and VFIO pins of unfaulted base pages and 2MB hugetlb pages now succeed and land on node 0 (correct). QEMU now starts with the same backend binding. Link: https://lore.kernel.org/20261018023349.1697434-1-gourry@gourry.net Fixes: 8e3560d963d2 ("mm: honor PF_MEMALLOC_PIN for all movable pages") Signed-off-by: Gregory Price (Meta) Signed-off-by: Andrew Morton Reviewed-by: Joshua Hahn Cc: David Hildenbrand Cc: Zi Yan Cc: Rakie Kim Cc: Ying Huang Cc: Pasha Tatashin Cc: Michal Hocko Cc: Signed-off-by: Sasha Levin --- mm/mempolicy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 197a5ea0d76d9..919a505cabaee 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2206,7 +2206,7 @@ static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol, break; case MPOL_BIND: /* Restrict to nodemask (but not on lower zones) */ - if (apply_policy_zone(pol, gfp_zone(gfp)) && + if (apply_policy_zone(pol, gfp_zone(current_gfp_context(gfp))) && cpuset_nodemask_valid_mems_allowed(&pol->nodes)) nodemask = &pol->nodes; if (pol->home_node != NUMA_NO_NODE) -- 2.53.0