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authorJoel Fernandes (Google) <joel@joelfernandes.org>2019-12-01 04:50:33 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-12-01 17:29:18 +0300
commite4dcad204d3a281be6f8573e0a82648a4ad84e69 (patch)
tree7c7d4a45f8a84ffe88078ad2def893eb35def96b /lib/vsprintf.c
parentb3d1411b6726ea6930222f8f12587d89762477c6 (diff)
downloadlinux-e4dcad204d3a281be6f8573e0a82648a4ad84e69.tar.xz
rss_stat: add support to detect RSS updates of external mm
When a process updates the RSS of a different process, the rss_stat tracepoint appears in the context of the process doing the update. This can confuse userspace that the RSS of process doing the update is updated, while in reality a different process's RSS was updated. This issue happens in reclaim paths such as with direct reclaim or background reclaim. This patch adds more information to the tracepoint about whether the mm being updated belongs to the current process's context (curr field). We also include a hash of the mm pointer so that the process who the mm belongs to can be uniquely identified (mm_id field). Also vsprintf.c is refactored a bit to allow reuse of hashing code. [akpm@linux-foundation.org: remove unused local `str'] [joelaf@google.com: inline call to ptr_to_hashval] Link: http://lore.kernel.org/r/20191113153816.14b95acd@gandalf.local.home Link: http://lkml.kernel.org/r/20191114164622.GC233237@google.com Link: http://lkml.kernel.org/r/20191106024452.81923-1-joel@joelfernandes.org Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Reported-by: Ioannis Ilkos <ilkos@google.com> Acked-by: Petr Mladek <pmladek@suse.com> [lib/vsprintf.c] Cc: Tim Murray <timmurray@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Carmen Jackson <carmenjackson@google.com> Cc: Mayank Gupta <mayankgupta@google.com> Cc: Daniel Colascione <dancol@google.com> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Minchan Kim <minchan@kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/vsprintf.c')
-rw-r--r--lib/vsprintf.c40
1 files changed, 29 insertions, 11 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index dee8fc467fcf..7c488a1ce318 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -761,11 +761,38 @@ static int __init initialize_ptr_random(void)
early_initcall(initialize_ptr_random);
/* Maps a pointer to a 32 bit unique identifier. */
+static inline int __ptr_to_hashval(const void *ptr, unsigned long *hashval_out)
+{
+ unsigned long hashval;
+
+ if (static_branch_unlikely(&not_filled_random_ptr_key))
+ return -EAGAIN;
+
+#ifdef CONFIG_64BIT
+ hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);
+ /*
+ * Mask off the first 32 bits, this makes explicit that we have
+ * modified the address (and 32 bits is plenty for a unique ID).
+ */
+ hashval = hashval & 0xffffffff;
+#else
+ hashval = (unsigned long)siphash_1u32((u32)ptr, &ptr_key);
+#endif
+ *hashval_out = hashval;
+ return 0;
+}
+
+int ptr_to_hashval(const void *ptr, unsigned long *hashval_out)
+{
+ return __ptr_to_hashval(ptr, hashval_out);
+}
+
static char *ptr_to_id(char *buf, char *end, const void *ptr,
struct printf_spec spec)
{
const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)";
unsigned long hashval;
+ int ret;
/* When debugging early boot use non-cryptographically secure hash. */
if (unlikely(debug_boot_weak_hash)) {
@@ -773,22 +800,13 @@ static char *ptr_to_id(char *buf, char *end, const void *ptr,
return pointer_string(buf, end, (const void *)hashval, spec);
}
- if (static_branch_unlikely(&not_filled_random_ptr_key)) {
+ ret = __ptr_to_hashval(ptr, &hashval);
+ if (ret) {
spec.field_width = 2 * sizeof(ptr);
/* string length must be less than default_width */
return error_string(buf, end, str, spec);
}
-#ifdef CONFIG_64BIT
- hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);
- /*
- * Mask off the first 32 bits, this makes explicit that we have
- * modified the address (and 32 bits is plenty for a unique ID).
- */
- hashval = hashval & 0xffffffff;
-#else
- hashval = (unsigned long)siphash_1u32((u32)ptr, &ptr_key);
-#endif
return pointer_string(buf, end, (const void *)hashval, spec);
}