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 4D6B711CAF; Fri, 22 May 2026 00:44:07 +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=1779410649; cv=none; b=sQynqwD/7JNUXlk6g73dAp23g8QKe+mFiNlMmKV18m1uB+Ur1C9rgeQ2XF/jUWyn8wvEuNm3cmzuxVw5mFSiMP0OZGO+hZUz0b94rf9b922bJ34cJKY4yojk5MePGm4Qeohodq8YP/8DfQ2Fg7N4ycgo5wX5xX99+GVkDmR28sU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779410649; c=relaxed/simple; bh=19YLvgtlMzU8ANelrSCykr6qqnrBqL0oi8/RpSbL01s=; h=Date:To:From:Subject:Message-Id; b=EzNnhJZMeBWY5ylAH8DYS4Dwtzu98QANHzbagJ7g5e+Svv4R7GFuJgIn6BPFvSidBHdAXafF5/Lriyp+p012K5r0n7ya0EU6oRhz00XAg6tPcXircZFEi6Da1lU1o3/lfN5Q32INRb8UZ+0PrWA6cFEJZyk7Gojphb2do5Kavvg= 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=lzOIcNAr; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="lzOIcNAr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C03401F000E9; Fri, 22 May 2026 00:44:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1779410647; bh=2JBhH1Zuv1KpnjGr18PzaaMKL6STg2UjLyqqaX6vLoE=; h=Date:To:From:Subject; b=lzOIcNAr83h1fzrFKhE/BCuWDSKkIPRs7bMTtLkheMA0cTywd7WzgjYDfF5i/TF+n OyoLqcdiLjZcWAYPFNGTNJJV5N0FwLVKNlsqU4KkC3IlCVOEEDPYFPU3UvVb7z6wh7 A+u/b5YKu5EXKaCHPy3M3XnclThjXmECQfHOZa9M= Date: Thu, 21 May 2026 17:44:07 -0700 To: mm-commits@vger.kernel.org,yuehaibing@huawei.com,stable@vger.kernel.org,osalvador@suse.de,muchun.song@linux.dev,david@kernel.org,almasrymina@google.com,devnexen@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-hugetlb-restore-reservation-on-error-in-hugetlb-folio-copy-paths.patch added to mm-hotfixes-unstable branch Message-Id: <20260522004407.C03401F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/hugetlb: restore reservation on error in hugetlb folio copy paths has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-hugetlb-restore-reservation-on-error-in-hugetlb-folio-copy-paths.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-restore-reservation-on-error-in-hugetlb-folio-copy-paths.patch This patch will later appear in the mm-hotfixes-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 various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: David Carlier Subject: mm/hugetlb: restore reservation on error in hugetlb folio copy paths Date: Wed, 20 May 2026 05:49:12 +0100 Two sites in mm/hugetlb.c allocate a hugetlb folio via alloc_hugetlb_folio() (consuming a VMA reservation) and then call copy_user_large_folio(), which became int-returning in commit 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults") and can now fail (e.g. -EHWPOISON on a hwpoisoned source page). On the failure path, folio_put() restores the global hugetlb pool count through free_huge_folio(), but the per-VMA reservation map entry is left marked consumed: - hugetlb_mfill_atomic_pte() resubmission path (UFFDIO_COPY) - copy_hugetlb_page_range() fork-time CoW path when hugetlb_try_dup_anon_rmap() fails (rare: pinned hugetlb anon folio under fork) User-visible effect: on UFFDIO_COPY into a private hugetlb VMA where the resubmission copy fails, the reservation for that address is leaked from the VMA's reserve map. A subsequent fault at the same address takes the no-reservation path, and under hugetlb pool pressure the task is SIGBUSed at an address it had previously reserved. The fork-time CoW path leaks the same way in the child VMA's reserve map, though it requires the much rarer combination of pinned hugetlb anon page + hwpoisoned source. Add the missing restore_reserve_on_error() call before folio_put() on both error paths. Link: https://lore.kernel.org/20260520044912.6751-1-devnexen@gmail.com Fixes: 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults") Signed-off-by: David Carlier Reviewed-by: Muchun Song Cc: David Hildenbrand Cc: Mina Almasry Cc: Muchun Song Cc: Oscar Salvador Cc: yuehaibing Cc: Signed-off-by: Andrew Morton --- mm/hugetlb.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/hugetlb.c~mm-hugetlb-restore-reservation-on-error-in-hugetlb-folio-copy-paths +++ a/mm/hugetlb.c @@ -4977,6 +4977,7 @@ again: addr, dst_vma); folio_put(pte_folio); if (ret) { + restore_reserve_on_error(h, dst_vma, addr, new_folio); folio_put(new_folio); break; } @@ -6273,6 +6274,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_ folio_put(*foliop); *foliop = NULL; if (ret) { + restore_reserve_on_error(h, dst_vma, dst_addr, folio); folio_put(folio); goto out; } _ Patches currently in -mm which might be from devnexen@gmail.com are mm-hugetlb-restore-reservation-on-error-in-hugetlb-folio-copy-paths.patch mm-page_io-rename-swap_iocb-fields-for-clarity.patch mm-shrinker-avoid-out-of-bounds-read-in-set_shrinker_bit.patch mm-swap-pm-hibernate-atomically-replace-hibernation-pin.patch