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authorMichal Hocko <mhocko@suse.com>2018-12-28 11:33:38 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 23:11:46 +0300
commit1c6fb1d89e73cd3bbfae7c400f1c615272aa435f (patch)
treefa6ef6cbbc6c726405762f5ccad2fe7302598cc9 /mm/debug.c
parent20ff1c950500380c6f74ec1a0d6f4eafab673ef6 (diff)
downloadlinux-1c6fb1d89e73cd3bbfae7c400f1c615272aa435f.tar.xz
mm: print more information about mapping in __dump_page
I have been promissing to improve memory offlining failures debugging for quite some time. As things stand now we get only very limited information in the kernel log when the offlining fails. It is usually only [ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed with no further details. We do not know what exactly fails and for what reason. Whenever I was forced to debug such a failure I've always had to do a debugging patch to tell me more. We can enable some tracepoints but it would be much better to get a better picture without using them. This patch series does 2 things. The first one is to make dump_page more usable by printing more information about the mapping patch 1. Then it reduces the log level from emerg to warning so that this function is usable from less critical context patch 2. Then I have added more detailed information about the offlining failure patch 4 and finally add dump_page to isolation and offlining migration paths. Patch 3 is a trivial cleanup. This patch (of 6): __dump_page prints the mapping pointer but that is quite unhelpful for many reports because the pointer itself only helps to distinguish anon/ksm mappings from other ones (because of lowest bits set). Sometimes it would be much more helpful to know what kind of mapping that is actually and if we know this is a file mapping then also try to resolve the dentry name. [dan.carpenter@oracle.com: fix a width vs precision bug in printk] Link: http://lkml.kernel.org/r/20181123072135.gqvblm2vdujbvfjs@kili.mountain [mhocko@kernel.org: use %dp to print dentry] Link: http://lkml.kernel.org/r/20181125080834.GB12455@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20181107101830.17405-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Cc: Oscar Salvador <OSalvador@suse.com> Cc: Baoquan He <bhe@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/debug.c')
-rw-r--r--mm/debug.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/mm/debug.c b/mm/debug.c
index cdacba12e09a..6d9aa5359109 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -44,6 +44,7 @@ const struct trace_print_flags vmaflag_names[] = {
void __dump_page(struct page *page, const char *reason)
{
+ struct address_space *mapping = page_mapping(page);
bool page_poisoned = PagePoisoned(page);
int mapcount;
@@ -70,6 +71,18 @@ void __dump_page(struct page *page, const char *reason)
if (PageCompound(page))
pr_cont(" compound_mapcount: %d", compound_mapcount(page));
pr_cont("\n");
+ if (PageAnon(page))
+ pr_emerg("anon ");
+ else if (PageKsm(page))
+ pr_emerg("ksm ");
+ else if (mapping) {
+ pr_emerg("%ps ", mapping->a_ops);
+ if (mapping->host->i_dentry.first) {
+ struct dentry *dentry;
+ dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
+ pr_emerg("name:\"%pd\" ", dentry);
+ }
+ }
BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
pr_emerg("flags: %#lx(%pGp)\n", page->flags, &page->flags);