From: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> Subject: [PATCH] proc: add /proc/kpagecskip interface This makes page pageblock skip on compaction information available to the user-space. Cc: Matt Mackall <mpm@xxxxxxxxxxx> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> --- Based on top of http://www.spinics.net/lists/linux-mm/msg35528.html patch. Example user-space usage has been added to: https://github.com/bzolnier/pagemap-demo-ng fs/proc/page.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) Index: b/fs/proc/page.c =================================================================== --- a/fs/proc/page.c 2012-11-29 12:06:10.408621309 +0100 +++ b/fs/proc/page.c 2012-11-29 12:11:19.760621273 +0100 @@ -339,12 +339,64 @@ static const struct file_operations proc .read = kpagetype_read, }; +#ifdef CONFIG_COMPACTION +static ssize_t kpagecskip_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + u64 __user *out = (u64 __user *)buf; + struct page *ppage; + unsigned long src = *ppos; + unsigned long pfn; + ssize_t ret = 0; + u64 pcskip; + + pfn = src / KPMSIZE; + count = min_t(unsigned long, count, + ((ARCH_PFN_OFFSET + max_pfn) * KPMSIZE) - src); + if (src & KPMMASK || count & KPMMASK) + return -EINVAL; + + while (count > 0) { + if (pfn_valid(pfn)) + ppage = pfn_to_page(pfn); + else + ppage = NULL; + if (!ppage) + pcskip = 0; + else + pcskip = get_pageblock_skip(ppage); + + if (put_user(pcskip, out)) { + ret = -EFAULT; + break; + } + + pfn++; + out++; + count -= KPMSIZE; + } + + *ppos += (char __user *)out - buf; + if (!ret) + ret = (char __user *)out - buf; + return ret; +} + +static const struct file_operations proc_kpagecskip_operations = { + .llseek = mem_lseek, + .read = kpagecskip_read, +}; +#endif + static int __init proc_page_init(void) { proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations); proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations); proc_create("kpageorder", S_IRUSR, NULL, &proc_kpageorder_operations); proc_create("kpagetype", S_IRUSR, NULL, &proc_kpagetype_operations); +#ifdef CONFIG_COMPACTION + proc_create("kpagecskip", S_IRUSR, NULL, &proc_kpagecskip_operations); +#endif return 0; } module_init(proc_page_init); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>