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author | Stephen Wilson <wilsons@start.ca> | 2011-05-24 17:12:49 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-25 08:39:35 -0700 |
commit | 5b52fc890bece77bffb9fade69239f71384ef02b (patch) | |
tree | 52848297984dba4c0f4106c5303a1a4bf0db92b0 /fs/proc | |
parent | f2beb7983613ecca20a61604f01ab50cc7a797e6 (diff) | |
download | linux-5b52fc890bece77bffb9fade69239f71384ef02b.tar.gz linux-5b52fc890bece77bffb9fade69239f71384ef02b.tar.bz2 linux-5b52fc890bece77bffb9fade69239f71384ef02b.zip |
proc: allocate storage for numa_maps statistics once
In show_numa_map() we collect statistics into a numa_maps structure.
Since the number of NUMA nodes can be very large, this structure is not a
candidate for stack allocation.
Instead of going thru a kmalloc()+kfree() cycle each time show_numa_map()
is invoked, perform the allocation just once when /proc/pid/numa_maps is
opened.
Performing the allocation when numa_maps is opened, and thus before a
reference to the target tasks mm is taken, eliminates a potential
stalemate condition in the oom-killer as originally described by Hugh
Dickins:
... imagine what happens if the system is out of memory, and the mm
we're looking at is selected for killing by the OOM killer: while
we wait in __get_free_page for more memory, no memory is freed
from the selected mm because it cannot reach exit_mmap while we hold
that reference.
Signed-off-by: Stephen Wilson <wilsons@start.ca>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/task_mmu.c | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 2ed53d18b2ef..2c9db29ea358 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -871,6 +871,11 @@ struct numa_maps { unsigned long node[MAX_NUMNODES]; }; +struct numa_maps_private { + struct proc_maps_private proc_maps; + struct numa_maps md; +}; + static void gather_stats(struct page *page, struct numa_maps *md, int pte_dirty) { int count = page_mapcount(page); @@ -963,9 +968,10 @@ static int gather_hugetbl_stats(pte_t *pte, unsigned long hmask, */ static int show_numa_map(struct seq_file *m, void *v) { - struct proc_maps_private *priv = m->private; + struct numa_maps_private *numa_priv = m->private; + struct proc_maps_private *proc_priv = &numa_priv->proc_maps; struct vm_area_struct *vma = v; - struct numa_maps *md; + struct numa_maps *md = &numa_priv->md; struct file *file = vma->vm_file; struct mm_struct *mm = vma->vm_mm; struct mm_walk walk = {}; @@ -976,9 +982,8 @@ static int show_numa_map(struct seq_file *m, void *v) if (!mm) return 0; - md = kzalloc(sizeof(struct numa_maps), GFP_KERNEL); - if (!md) - return 0; + /* Ensure we start with an empty set of numa_maps statistics. */ + memset(md, 0, sizeof(*md)); md->vma = vma; @@ -987,7 +992,7 @@ static int show_numa_map(struct seq_file *m, void *v) walk.private = md; walk.mm = mm; - pol = get_vma_policy(priv->task, vma, vma->vm_start); + pol = get_vma_policy(proc_priv->task, vma, vma->vm_start); mpol_to_str(buffer, sizeof(buffer), pol, 0); mpol_cond_put(pol); @@ -1034,12 +1039,12 @@ static int show_numa_map(struct seq_file *m, void *v) seq_printf(m, " N%d=%lu", n, md->node[n]); out: seq_putc(m, '\n'); - kfree(md); if (m->count < m->size) - m->version = (vma != priv->tail_vma) ? vma->vm_start : 0; + m->version = (vma != proc_priv->tail_vma) ? vma->vm_start : 0; return 0; } + static const struct seq_operations proc_pid_numa_maps_op = { .start = m_start, .next = m_next, @@ -1049,7 +1054,20 @@ static const struct seq_operations proc_pid_numa_maps_op = { static int numa_maps_open(struct inode *inode, struct file *file) { - return do_maps_open(inode, file, &proc_pid_numa_maps_op); + struct numa_maps_private *priv; + int ret = -ENOMEM; + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (priv) { + priv->proc_maps.pid = proc_pid(inode); + ret = seq_open(file, &proc_pid_numa_maps_op); + if (!ret) { + struct seq_file *m = file->private_data; + m->private = priv; + } else { + kfree(priv); + } + } + return ret; } const struct file_operations proc_numa_maps_operations = { |