From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E7B083B5DED for ; Mon, 20 Jul 2026 14:22:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784557381; cv=none; b=RmUu6e4Eq/cSNzTkcF9cvNmHfXneSqRfBLhQk64Sw4qlFGEoCXcJjnM7wEFnWUD8CSvla/+SX1/q2K0uR4ah41/nADFthwSRjneyhmDuzcoyR4CGRT9FevU2siFUdLtH4n7bkhwjr//miVQu/wQzPBiVjsd+JkYhxV5ytFNJNDs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784557381; c=relaxed/simple; bh=x6d1Ea1DDiCL1TdlICCOsMTjTWAb+MAbK6aDGWyqt5U=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=A2gl5+S8GVyQAANk0zbx2v8T+J7AuOfWwePe0b/+oBKDah6vWDivWr7Zf4eCkS7aLw+JnSPpPD1OqgBu4ZrwqFUTP3sD+0vxKDGSkZvHj8e894H+PfhVpF63QBLbVeKs/klXxoVqIlH3hb8lsPye25V5cKwR6yPiKT7dHDPj7hQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bHUmCerZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="bHUmCerZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20A8A1F000E9; Mon, 20 Jul 2026 14:22:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784557379; bh=RSGzR039xzf58pLYpEmBOcRecWc0kkAkmNYvPZxgZwk=; h=Subject:To:Cc:From:Date; b=bHUmCerZuzqoe5LZsam5kGExBnYDafJ7gqp6b4HI0b/cPpcbNgz+z1+J3iY17O3Sk SvNcaH2trDHO7vOBnCqHKRepmPz0F1tr/ku4cbzX3rllNt/9kMAwdDrcE6uFF+rhK+ vQTkqTWTMricMQ5kU4iTBKcO8ifPEaU05hL0o1sE= Subject: FAILED: patch "[PATCH] mm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch" failed to apply to 5.15-stable tree To: kartikey406@gmail.com,akpm@linux-foundation.org,almasrymina@google.com,david@kernel.org,muchun.song@linux.dev,osalvador@suse.de,stable@vger.kernel.org Cc: From: Date: Mon, 20 Jul 2026 16:22:40 +0200 Message-ID: <2026072040-upwind-squeamish-05f0@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 15807d0ddde37407af72859426b654f3d1972b00 # git commit -s git send-email --to '' --in-reply-to '2026072040-upwind-squeamish-05f0@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 15807d0ddde37407af72859426b654f3d1972b00 Mon Sep 17 00:00:00 2001 From: Deepanshu Kartikey Date: Sat, 28 Mar 2026 12:25:34 +0530 Subject: [PATCH] mm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch In alloc_hugetlb_folio(), a single h_cg pointer is used for both the rsvd and non-rsvd hugetlb cgroup charges. When map_chg is set, hugetlb_cgroup_charge_cgroup_rsvd() stores the charged cgroup in h_cg, but the immediately following hugetlb_cgroup_charge_cgroup() overwrites h_cg with the non-rsvd cgroup pointer. As a result, hugetlb_cgroup_commit_charge_rsvd() stores the wrong (non-rsvd) cgroup pointer into the folio's rsvd slot. When the folio is later freed, free_huge_folio() unconditionally calls both hugetlb_cgroup_uncharge_folio() and hugetlb_cgroup_uncharge_folio_rsvd(). The rsvd uncharge reads back the wrong cgroup from the folio and decrements a counter that was never charged for that cgroup, causing a page_counter underflow: page_counter underflow: -512 nr_pages=512 WARNING: mm/page_counter.c:61 at page_counter_cancel Fix this by introducing a separate h_cg_rsvd pointer exclusively for the rsvd charge path, keeping the rsvd and non-rsvd charges fully independent through their charge, commit, and error uncharge paths. Link: https://lore.kernel.org/20260328065534.346053-1-kartikey406@gmail.com Fixes: 08cf9faf7558 ("hugetlb_cgroup: support noreserve mappings") Reported-by: syzbot+226c1f947186f8fef796@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=226c1f947186f8fef796 Signed-off-by: Deepanshu Kartikey Reviewed-by: Muchun Song Cc: David Hildenbrand Cc: Oscar Salvador Cc: Mina Almasry Cc: Signed-off-by: Andrew Morton diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 4b80b167cc9c..bcc657abbe35 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2859,6 +2859,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, map_chg_state map_chg; int ret, idx; struct hugetlb_cgroup *h_cg = NULL; + struct hugetlb_cgroup *h_cg_rsvd = NULL; gfp_t gfp = htlb_alloc_mask(h) | __GFP_RETRY_MAYFAIL; idx = hstate_index(h); @@ -2909,7 +2910,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, */ if (map_chg) { ret = hugetlb_cgroup_charge_cgroup_rsvd( - idx, pages_per_huge_page(h), &h_cg); + idx, pages_per_huge_page(h), &h_cg_rsvd); if (ret) goto out_subpool_put; } @@ -2951,7 +2952,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, */ if (map_chg) { hugetlb_cgroup_commit_charge_rsvd(idx, pages_per_huge_page(h), - h_cg, folio); + h_cg_rsvd, folio); } spin_unlock_irq(&hugetlb_lock); @@ -3003,7 +3004,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma, out_uncharge_cgroup_reservation: if (map_chg) hugetlb_cgroup_uncharge_cgroup_rsvd(idx, pages_per_huge_page(h), - h_cg); + h_cg_rsvd); out_subpool_put: /* * put page to subpool iff the quota of subpool's rsv_hpages is used