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 681532900BE for ; Tue, 22 Apr 2025 19:17:59 +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=1745349479; cv=none; b=jFz0ggj/ezJD4vjejeLuQFE16jpTsfDrkiRfHcf97RjOFNJM+eJN2kAble/MedX8i6bSUzA4E+LvQRf56jOFlxVJn0OQmNtY1XNS4TzqoNjuvAq6l8VnP+ViApZ3XuxpQGClBb7MIwN+HKUyrghmt3ySv3C9IUcQMa1nc9Jr+jA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745349479; c=relaxed/simple; bh=ARlH4/D0/wFdMAuGA5p0ziwhJld/gjefff8IhPXKYDM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=EQ+hxpNfckL308YSn6bJXqZoRKoqmZHHv2Si79qkIjdU0snG0UX3OiehK/sjuM2u79yYUz/XubS2Bs/p3XfOqXO+/TLFAnwD5J413h8/3NHBOzlxNkWHleIjfYjniSyvuf4efGhO0RAro/IvD4sjp6J+BOAoaT3LyBBac859VdU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UTjFgICN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UTjFgICN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B355AC4CEE9; Tue, 22 Apr 2025 19:17:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745349478; bh=ARlH4/D0/wFdMAuGA5p0ziwhJld/gjefff8IhPXKYDM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UTjFgICNg1OMMAlJVf2xy0PD4sCBcXbr1G0zuMKZIBHLg0A0GnoUaO+7iJtTECYRG dT4h2WinzFiS8tcV25TsWoT4lwIbT4BoYMqDEsD1X5gChFb/w35Wm3gjlzNGI3OWOE wJ/rsEiQeGlthDZWqlU+79QmJ1RMgyYMGsHvdAegk9dj4DTvYA48yKD4B2WjZB9R4a AOt3CR/AQewQdQIlpjDw8SgTMx5R36jRrzVKJDF1Xn6BAMiXBjxUjhfC1mXIFa3Aqo Yz8zUEkjtHtymWyUksf+oYwmcYBmfkjTPJ1K0xhHBgpT5ZDxmKROwO8k7t8TVpy8Rf h6Wf0GJxF2oQg== From: Sasha Levin To: stable@vger.kernel.org, lorenzo.stoakes@oracle.com Cc: Sasha Levin Subject: Re: [PATCH 6.12.y] mm/vma: add give_up_on_oom option on modify/merge, use in uffd release Date: Tue, 22 Apr 2025 15:17:56 -0400 Message-Id: <20250422123659-a06f5f388320cbae@stable.kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250422113216.110404-1-lorenzo.stoakes@oracle.com> References: Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Sasha's backport helper bot ] Hi, Summary of potential issues: ⚠️ Found matching upstream commit but patch is missing proper reference to it Found matching upstream commit: 41e6ddcaa0f18dda4c3fadf22533775a30d6f72f Status in newer kernel trees: 6.14.y | Not found Note: The patch differs from the upstream commit: --- 1: 41e6ddcaa0f18 ! 1: 80c1bca5589f9 mm/vma: add give_up_on_oom option on modify/merge, use in uffd release @@ Commit message Suggested-by: Jann Horn Cc: Signed-off-by: Andrew Morton + (cherry picked from commit 41e6ddcaa0f18dda4c3fadf22533775a30d6f72f) ## mm/userfaultfd.c ## @@ mm/userfaultfd.c: struct vm_area_struct *userfaultfd_clear_vma(struct vma_iterator *vmi, @@ mm/userfaultfd.c: int userfaultfd_register_range(struct userfaultfd_ctx *ctx, ## mm/vma.c ## -@@ mm/vma.c: static void vmg_adjust_set_range(struct vma_merge_struct *vmg) - /* - * Actually perform the VMA merge operation. - * -+ * IMPORTANT: We guarantee that, should vmg->give_up_on_oom is set, to not -+ * modify any VMAs or cause inconsistent state should an OOM condition arise. -+ * - * Returns 0 on success, or an error value on failure. - */ - static int commit_merge(struct vma_merge_struct *vmg) -@@ mm/vma.c: static int commit_merge(struct vma_merge_struct *vmg) - - init_multi_vma_prep(&vp, vma, vmg); - -+ /* -+ * If vmg->give_up_on_oom is set, we're safe, because we don't actually -+ * manipulate any VMAs until we succeed at preallocation. -+ * -+ * Past this point, we will not return an error. -+ */ - if (vma_iter_prealloc(vmg->vmi, vma)) - return -ENOMEM; - -@@ mm/vma.c: static __must_check struct vm_area_struct *vma_merge_existing_range( +@@ mm/vma.c: static struct vm_area_struct *vma_merge_existing_range(struct vma_merge_struct * if (anon_dup) unlink_anon_vmas(anon_dup); @@ mm/vma.c: static __must_check struct vm_area_struct *vma_merge_existing_range( return NULL; } -@@ mm/vma.c: static __must_check struct vm_area_struct *vma_merge_existing_range( +@@ mm/vma.c: static struct vm_area_struct *vma_merge_existing_range(struct vma_merge_struct * abort: vma_iter_set(vmg->vmi, start); vma_iter_load(vmg->vmi); @@ mm/vma.c: static __must_check struct vm_area_struct *vma_merge_existing_range( return NULL; } -@@ mm/vma.c: int vma_expand(struct vma_merge_struct *vmg) - /* This should already have been checked by this point. */ - VM_WARN_ON_VMG(!can_merge_remove_vma(next), vmg); - vma_start_write(next); -+ /* -+ * In this case we don't report OOM, so vmg->give_up_on_mm is -+ * safe. -+ */ - ret = dup_anon_vma(middle, next, &anon_dup); - if (ret) - return ret; @@ mm/vma.c: int vma_expand(struct vma_merge_struct *vmg) return 0; @@ mm/vma.c: struct vm_area_struct ## mm/vma.h ## @@ mm/vma.h: struct vma_merge_struct { - */ - bool just_expand :1; - + struct anon_vma_name *anon_name; + enum vma_merge_flags merge_flags; + enum vma_merge_state state; ++ + /* + * If a merge is possible, but an OOM error occurs, give up and don't + * execute the merge, returning NULL. + */ + bool give_up_on_oom :1; -+ - /* Internal flags set during merge process: */ + }; - /* -@@ mm/vma.h: __must_check struct vm_area_struct + static inline bool vmg_nomem(struct vma_merge_struct *vmg) +@@ mm/vma.h: struct vm_area_struct struct vm_area_struct *vma, unsigned long start, unsigned long end, unsigned long new_flags, @@ mm/vma.h: __must_check struct vm_area_struct + struct vm_userfaultfd_ctx new_ctx, + bool give_up_on_oom); - __must_check struct vm_area_struct - *vma_merge_new_range(struct vma_merge_struct *vmg); + struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg); + --- Results of testing on various branches: | Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-6.12.y | Success | Success |