Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758605Ab2JXM1g (ORCPT ); Wed, 24 Oct 2012 08:27:36 -0400 Received: from mail-la0-f46.google.com ([209.85.215.46]:55552 "EHLO mail-la0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755645Ab2JXM1e (ORCPT ); Wed, 24 Oct 2012 08:27:34 -0400 Date: Wed, 24 Oct 2012 16:27:30 +0400 From: Cyrill Gorcunov To: Andrew Morton Cc: LKML , Pavel Emelyanov , Peter Zijlstra , Stephen Rothwell Subject: [PATCH -mm] procfs: add VmFlags field in smaps output v3 Message-ID: <20121024122730.GO30983@moon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6672 Lines: 181 During c/r sessions we've found that there is no way at the moment to fetch some VMA associated flags, such as mlock() and madvise(). This leads us to a problem -- we don't know if we should call for mlock() and/or madvise() after restore on the vma area we're bringing back to life. This patch intorduces a new field into "smaps" output called VmFlags, where all set flags associated with the particular VMA is shown as two letter mnemonics. [ Strictly speaking for c/r we only need mlock/madvise bits but it has been said that providing just a few flags looks somehow inconsistent. So all flags are here now. ] This feature is made available on CONFIG_CHECKPOINT_RESTORE=n kernels, as other applications may start to use these fields. The data is encoded in a somewhat awkward two letters mnemonic form, to encourage userspace to be prepared for fields being added or removed in the future. [peterz: props to use for_each_set_bit] [stephen: props to use array instead of struct] [akpm: overall redesign and simplification] Signed-off-by: Cyrill Gorcunov Cc: Pavel Emelyanov Cc: Peter Zijlstra Cc: Stephen Rothwell Cc: Andrew Morton --- Andrew, this patch is one instead of all those small series which is in -mm tree now. If there will be no more comments could you please substitute the existing series with it. Documentation/filesystems/proc.txt | 40 +++++++++++++++++++++++++++- fs/proc/task_mmu.c | 52 +++++++++++++++++++++++++++++++++++++ 2 files changed, 90 insertions(+), 2 deletions(-) Index: linux-2.6.git/Documentation/filesystems/proc.txt =================================================================== --- linux-2.6.git.orig/Documentation/filesystems/proc.txt +++ linux-2.6.git/Documentation/filesystems/proc.txt @@ -142,7 +142,7 @@ Table 1-1: Process specific entries in / pagemap Page table stack Report full stack trace, enable via CONFIG_STACKTRACE smaps a extension based on maps, showing the memory consumption of - each mapping + each mapping and flags associated with it .............................................................................. For example, to get the status information of a process, all you have to do is @@ -415,8 +415,9 @@ Swap: 0 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Locked: 374 kB +VmFlags: rd ex mr mw me de -The first of these lines shows the same information as is displayed for the +the first of these lines shows the same information as is displayed for the mapping in /proc/PID/maps. The remaining lines show the size of the mapping (size), the amount of the mapping that is currently resident in RAM (RSS), the process' proportional share of this mapping (PSS), the number of clean and @@ -430,6 +431,41 @@ and a page is modified, the file page is "Swap" shows how much would-be-anonymous memory is also used, but out on swap. +"VmFlags" field deserves a separate description. This member represents the kernel +flags associated with the particular virtual memory area in two letter encoded +manner. The codes are the following: + rd - readable + wr - writeable + ex - executable + sh - shared + mr - may read + mw - may write + me - may execute + ms - may share + gd - stack segment growns down + pf - pure PFN range + dw - disabled write to the mapped file + lo - pages are locked in memory + io - memory mapped I/O area + sr - sequential read advise provided + rr - random read advise provided + dc - do not copy area on fork + de - do not expand area on remapping + ac - area is accountable + nr - swap space is not reserved for the area + ht - area uses huge tlb pages + nl - non-linear mapping + ar - architecture specific flag + dd - do not include area into core dump + mm - mixed map area + hg - huge page advise flag + nh - no-huge page advise flag + mg - mergable advise flag + +Note that there is no guarantee that every flag and associated mnemonic will +be present in all further kernel releases. Things get changed, the flags may +be vanished or the reverse -- new added. + This file is only present if the CONFIG_MMU kernel configuration option is enabled. Index: linux-2.6.git/fs/proc/task_mmu.c =================================================================== --- linux-2.6.git.orig/fs/proc/task_mmu.c +++ linux-2.6.git/fs/proc/task_mmu.c @@ -480,6 +480,56 @@ static int smaps_pte_range(pmd_t *pmd, u return 0; } +static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma) +{ + /* + * Don't forget to update Documentation/ on changes. + */ + static const char mnemonics[BITS_PER_LONG][2] = { + /* + * In case if we meet a flag we don't know about. + */ + [0 ... (BITS_PER_LONG-1)] = { "??" }, + + [ilog2(VM_READ)] = "rd", + [ilog2(VM_WRITE)] = "wr", + [ilog2(VM_EXEC)] = "ex", + [ilog2(VM_SHARED)] = "sh", + [ilog2(VM_MAYREAD)] = "mr", + [ilog2(VM_MAYWRITE)] = "mw", + [ilog2(VM_MAYEXEC)] = "me", + [ilog2(VM_MAYSHARE)] = "ms", + [ilog2(VM_GROWSDOWN)] = "gd", + [ilog2(VM_PFNMAP)] = "pf", + [ilog2(VM_DENYWRITE)] = "dw", + [ilog2(VM_LOCKED)] = "lo", + [ilog2(VM_IO)] = "io", + [ilog2(VM_SEQ_READ)] = "sr", + [ilog2(VM_RAND_READ)] = "rr", + [ilog2(VM_DONTCOPY)] = "dc", + [ilog2(VM_DONTEXPAND)] = "de", + [ilog2(VM_ACCOUNT)] = "ac", + [ilog2(VM_NORESERVE)] = "nr", + [ilog2(VM_HUGETLB)] = "ht", + [ilog2(VM_NONLINEAR)] = "nl", + [ilog2(VM_ARCH_1)] = "ar", + [ilog2(VM_DONTDUMP)] = "dd", + [ilog2(VM_MIXEDMAP)] = "mm", + [ilog2(VM_HUGEPAGE)] = "hg", + [ilog2(VM_NOHUGEPAGE)] = "nh", + [ilog2(VM_MERGEABLE)] = "mg", + }; + size_t i; + + seq_puts(m, "VmFlags: "); + for_each_set_bit(i, &vma->vm_flags, BITS_PER_LONG) { + seq_printf(m, "%c%c ", + mnemonics[i][0], + mnemonics[i][1]); + } + seq_putc(m, '\n'); +} + static int show_smap(struct seq_file *m, void *v, int is_pid) { struct proc_maps_private *priv = m->private; @@ -535,6 +585,8 @@ static int show_smap(struct seq_file *m, seq_printf(m, "Nonlinear: %8lu kB\n", mss.nonlinear >> 10); + show_smap_vma_flags(m, vma); + if (m->count < m->size) /* vma is copied successfully */ m->version = (vma != get_gate_vma(task->mm)) ? vma->vm_start : 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/