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 286332E7F1A; Sat, 14 Jun 2025 13:49:12 +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=1749908952; cv=none; b=ZCpjvbLvsJHlZblW7YI0g9hi5wDr6RB+wxTuZsIdsIlxD9WXJUvnau2ut125+ExLC9hPmmlOdO4Di2wE6OyUFhU9r0AyJVcTI5oPBGrxIHipQOTnB6gPK2FEphS1GwVErp7/CZbc2r/nrSlDYk096iy0x0o/3OvuWj/XXPyA0A8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749908952; c=relaxed/simple; bh=zS8ZFG4HpWsJFM53jLyQzCNYlIU54deOx6WKkgpE/6M=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=fbE98vsPaSKzq4QagMECsaNzRapsiZ/V99Wno3LvCbbmmGgLWuLFLS8ptcMhhgJdj/GwogHJFo0iplaG4Dwx9EZdG4fTOk598jMxV+81AuQtDTTJsk9WnvrvIyt+KQlA0yaJKSOUdaQEql2vJ4HGi2UqxbmWlMuYRmruUC8PDeE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=k58zgvBL; 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="k58zgvBL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65B13C4CEEE; Sat, 14 Jun 2025 13:49:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749908952; bh=zS8ZFG4HpWsJFM53jLyQzCNYlIU54deOx6WKkgpE/6M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=k58zgvBLLy0GEluPrFS97RLZTXqYzyMII1P2FBtNLubbBpcLo6eDz037z66PqhQWq c5WR6OMwXXrx21oJbG2Ygwf8wjTqheqhSt3uJ4MZIbYq9l/pUABWNUxWMyd6otiJt6 NfvW/8KdkxUyEw727dM9gz5VtQZ1czcJr4IDxEVgwbaGZW5hTAlf+yLa0EZh/7topF QpdjGgn5gvq2lut7ivNMLaqZp5KTwrN9021R1lN/wKMsXeMHUtcBhilRTz85fTwwfD aIBH8OC5ATf0f0iepRflqRNO+sVkG4U58QiuvRlUAGC61raQEvyAun/6/BBq8yUODQ fCgcoHJXiIwhw== From: Sasha Levin To: linux-kernel@vger.kernel.org Cc: linux-api@vger.kernel.org, workflows@vger.kernel.org, tools@kernel.org, Sasha Levin Subject: [RFC 12/19] mm/mlock: add API specification for mlockall Date: Sat, 14 Jun 2025 09:48:51 -0400 Message-Id: <20250614134858.790460-13-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250614134858.790460-1-sashal@kernel.org> References: <20250614134858.790460-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add kernel API specification for the mlockall() system call. Signed-off-by: Sasha Levin --- mm/mlock.c | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) diff --git a/mm/mlock.c b/mm/mlock.c index af2ab78acc226..95ee707c5922f 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -997,6 +997,150 @@ static int apply_mlockall_flags(int flags) return 0; } + +DEFINE_KERNEL_API_SPEC(sys_mlockall) + KAPI_DESCRIPTION("Lock all process pages in memory") + KAPI_LONG_DESC("Locks all pages mapped into the process address space. " + "MCL_CURRENT locks current pages, MCL_FUTURE locks future mappings, " + "MCL_ONFAULT defers locking until page fault.") + KAPI_CONTEXT(KAPI_CTX_PROCESS | KAPI_CTX_SLEEPABLE) + + /* Parameters */ + KAPI_PARAM(0, "flags", "int", "Flags controlling which pages to lock") + KAPI_PARAM_FLAGS(KAPI_PARAM_IN) + .type = KAPI_TYPE_INT, + .constraint_type = KAPI_CONSTRAINT_MASK, + .valid_mask = MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT, + .constraints = "Must specify MCL_CURRENT and/or MCL_FUTURE; MCL_ONFAULT can be OR'd", + KAPI_PARAM_END + + /* Return specification */ + KAPI_RETURN("long", "0 on success, negative error code on failure") + .type = KAPI_TYPE_INT, + .check_type = KAPI_RETURN_ERROR_CHECK, + .success_value = 0, + KAPI_RETURN_END + + /* Error codes */ + KAPI_ERROR(0, -EINVAL, "EINVAL", "Invalid flags", "Invalid combination of flags specified, or no flags set, or only MCL_ONFAULT without MCL_CURRENT or MCL_FUTURE.") + KAPI_ERROR(1, -EPERM, "EPERM", "Insufficient privileges", "The caller is not privileged (no CAP_IPC_LOCK) and RLIMIT_MEMLOCK is 0.") + KAPI_ERROR(2, -ENOMEM, "ENOMEM", "Insufficient resources", "MCL_CURRENT is set and total VM size exceeds RLIMIT_MEMLOCK and caller lacks CAP_IPC_LOCK.") + KAPI_ERROR(3, -EINTR, "EINTR", "Interrupted by signal", "The operation was interrupted by a signal before completion.") + KAPI_ERROR(4, -EAGAIN, "EAGAIN", "Some memory could not be locked", "Some pages could not be locked, possibly due to memory pressure.") + + /* Signal specifications */ + KAPI_SIGNAL(0, 0, "FATAL_SIGNALS", KAPI_SIGNAL_RECEIVE, KAPI_SIGNAL_ACTION_RETURN) + KAPI_SIGNAL_CONDITION("Fatal signal pending during mmap_write_lock_killable") + KAPI_SIGNAL_DESC("Fatal signals (SIGKILL, SIGTERM, etc.) can interrupt the operation when acquiring mmap_write_lock_killable(), causing -EINTR return") + KAPI_SIGNAL_RESTARTABLE + KAPI_SIGNAL_END + + KAPI_SIGNAL(1, SIGBUS, "SIGBUS", KAPI_SIGNAL_SEND, KAPI_SIGNAL_ACTION_DEFAULT) + KAPI_SIGNAL_TARGET("Current process") + KAPI_SIGNAL_CONDITION("Memory access to locked page fails") + KAPI_SIGNAL_DESC("Can be generated later if accessing a locked page that cannot be brought into memory (e.g., truncated file mapping)") + KAPI_SIGNAL_END + + /* Side effects */ + KAPI_SIDE_EFFECT(0, KAPI_EFFECT_MODIFY_STATE | KAPI_EFFECT_ALLOC_MEMORY, + "all process memory", + "Locks all current pages into physical memory, preventing swapping") + KAPI_EFFECT_REVERSIBLE + KAPI_EFFECT_CONDITION("MCL_CURRENT flag set") + KAPI_SIDE_EFFECT_END + + KAPI_SIDE_EFFECT(1, KAPI_EFFECT_MODIFY_STATE, + "mm->def_flags", + "Sets VM_LOCKED in default flags for future mappings") + KAPI_EFFECT_REVERSIBLE + KAPI_EFFECT_CONDITION("MCL_FUTURE flag set") + KAPI_SIDE_EFFECT_END + + KAPI_SIDE_EFFECT(2, KAPI_EFFECT_MODIFY_STATE, + "mm->locked_vm", + "Increases process locked memory counter for entire address space") + KAPI_EFFECT_REVERSIBLE + KAPI_EFFECT_CONDITION("MCL_CURRENT flag set") + KAPI_SIDE_EFFECT_END + + KAPI_SIDE_EFFECT(3, KAPI_EFFECT_ALLOC_MEMORY, + "page tables", + "May allocate and populate page table entries for all mappings") + KAPI_EFFECT_CONDITION("MCL_CURRENT without MCL_ONFAULT") + KAPI_SIDE_EFFECT_END + + KAPI_SIDE_EFFECT(4, KAPI_EFFECT_MODIFY_STATE, + "VMA flags", + "Sets VM_LOCKED on all existing VMAs") + KAPI_EFFECT_REVERSIBLE + KAPI_EFFECT_CONDITION("MCL_CURRENT flag set") + KAPI_SIDE_EFFECT_END + + KAPI_SIDE_EFFECT(5, KAPI_EFFECT_SCHEDULE, + "mm_populate", + "Triggers population of entire address space") + KAPI_EFFECT_CONDITION("MCL_CURRENT without MCL_ONFAULT") + KAPI_SIDE_EFFECT_END + + /* State transitions */ + KAPI_STATE_TRANS(0, "all memory pages", + "swappable", "locked in RAM", + "All pages in process become non-swappable") + KAPI_STATE_TRANS_COND("MCL_CURRENT flag set") + KAPI_STATE_TRANS_END + + KAPI_STATE_TRANS(1, "future mappings", + "normal", "auto-locked", + "New mappings will be automatically locked") + KAPI_STATE_TRANS_COND("MCL_FUTURE flag set") + KAPI_STATE_TRANS_END + + KAPI_STATE_TRANS(2, "VMA flags", + "varied", "all VM_LOCKED", + "All virtual memory areas marked as locked") + KAPI_STATE_TRANS_COND("MCL_CURRENT flag set") + KAPI_STATE_TRANS_END + + KAPI_STATE_TRANS(3, "page fault behavior", + "normal faulting", "lock on fault", + "Pages locked when faulted in rather than immediately") + KAPI_STATE_TRANS_COND("MCL_ONFAULT flag set") + KAPI_STATE_TRANS_END + + KAPI_STATE_TRANS(4, "process statistics", + "partial locked memory", "all memory locked", + "Entire VM size counted against RLIMIT_MEMLOCK") + KAPI_STATE_TRANS_COND("MCL_CURRENT flag set") + KAPI_STATE_TRANS_END + + /* Locking information */ + KAPI_LOCK(0, "mmap_lock", KAPI_LOCK_RWLOCK) + KAPI_LOCK_DESC("Process memory map write lock") + KAPI_LOCK_ACQUIRED + KAPI_LOCK_RELEASED + KAPI_LOCK_DESC("Protects VMA modifications during mlockall operation") + KAPI_LOCK_END + + KAPI_LOCK(1, "lru_lock", KAPI_LOCK_SPINLOCK) + KAPI_LOCK_DESC("Per-memcg LRU list lock") + KAPI_LOCK_ACQUIRED + KAPI_LOCK_RELEASED + KAPI_LOCK_DESC("Taken when moving pages to unevictable list for all locked pages") + KAPI_LOCK_END + + .error_count = 5, + .param_count = 1, + .since_version = "2.0", + .signal_count = 2, + .side_effect_count = 6, + .state_trans_count = 5, + .lock_count = 2, + .examples = "mlockall(MCL_CURRENT); // Lock current mappings\n" + "mlockall(MCL_CURRENT | MCL_FUTURE); // Lock current and future\n" + "mlockall(MCL_CURRENT | MCL_ONFAULT); // Lock current on fault", + .notes = "Affects all current VMAs and optionally future mappings via mm->def_flags", +KAPI_END_SPEC; + SYSCALL_DEFINE1(mlockall, int, flags) { unsigned long lock_limit; -- 2.39.5