Re: mpol_to_str revisited.
From: David Rientjes <rientjes@google.com>
Date: 2012-10-08 20:35:57
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On Mon, 8 Oct 2012, Dave Jones wrote:
unanswered question: why are the buffer sizes here different ? which is correct?
Given the current set of mempolicy modes and flags, it's 34, but this can change if new modes or flags are added with longer names. I see no reason why shmem shouldn't round up to the nearest power-of-2 of 64 like it already does, but 50 is certainly safe as well in task_mmu.c.
quoted hunk ↗ jump to hunk
diff -durpN '--exclude-from=/home/davej/.exclude' src/git-trees/kernel/linux/fs/proc/task_mmu.c linux-dj/fs/proc/task_mmu.c--- src/git-trees/kernel/linux/fs/proc/task_mmu.c 2012-05-31 22:32:46.778150675 -0400 +++ linux-dj/fs/proc/task_mmu.c 2012-10-04 19:31:41.269988984 -0400@@ -1162,6 +1162,7 @@ static int show_numa_map(struct seq_file struct mm_walk walk = {}; struct mempolicy *pol; int n; + int ret; char buffer[50]; if (!mm)@@ -1178,7 +1179,11 @@ static int show_numa_map(struct seq_file walk.mm = mm; pol = get_vma_policy(proc_priv->task, vma, vma->vm_start); - mpol_to_str(buffer, sizeof(buffer), pol, 0); + memset(buffer, 0, sizeof(buffer)); + ret = mpol_to_str(buffer, sizeof(buffer), pol, 0); + if (ret < 0) + return 0;
We should need the mpol_cond_put(pol) here before returning.
quoted hunk ↗ jump to hunk
+ mpol_cond_put(pol); seq_printf(m, "%08lx %s", vma->vm_start, buffer); diff -durpN '--exclude-from=/home/davej/.exclude' src/git-trees/kernel/linux/mm/shmem.c linux-dj/mm/shmem.c--- src/git-trees/kernel/linux/mm/shmem.c 2012-10-02 15:49:51.977277944 -0400 +++ linux-dj/mm/shmem.c 2012-10-04 19:32:28.862949907 -0400@@ -885,13 +885,15 @@ redirty: static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) { char buffer[64]; + int ret; if (!mpol || mpol->mode == MPOL_DEFAULT) return; /* show nothing */ - mpol_to_str(buffer, sizeof(buffer), mpol, 1); - - seq_printf(seq, ",mpol=%s", buffer); + memset(buffer, 0, sizeof(buffer)); + ret = mpol_to_str(buffer, sizeof(buffer), mpol, 1); + if (ret > 0) + seq_printf(seq, ",mpol=%s", buffer); } static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
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