commit 8e6853c58056281ec2386b05c12ea4a1d6c03929
author Treehugger Robot <treehugger-gerrit@google.com> Wed Nov 28 04:00:12 2018 +0000
committer Gerrit Code Review <noreply-gerritcodereview@google.com> Wed Nov 28 04:00:12 2018 +0000
tree 7ae68078243492a6a4fe566b97b4edfac74ad286
parent 9c62459983cb776b037e282863622ab8a8481c20
parent 918b11c0903cfb8f00d4008806463c4b7a29e3c8

Merge "Reduce logging around segfaults"

libmemunreachable/HeapWalker.cpp

diff --git a/libmemunreachable/HeapWalker.cpp b/libmemunreachable/HeapWalker.cpp
index 2403ad0..a046dad 100644
--- a/libmemunreachable/HeapWalker.cpp
+++ b/libmemunreachable/HeapWalker.cpp
@@ -76,12 +76,14 @@
     Range range = to_do.back();
     to_do.pop_back();
 
+    walking_range_ = range;
     ForEachPtrInRange(range, [&](Range& ref_range, AllocationInfo* ref_info) {
       if (!ref_info->referenced_from_root) {
         ref_info->referenced_from_root = true;
         to_do.push_back(ref_range);
       }
     });
+    walking_range_ = Range{0, 0};
   }
 }
 
@@ -113,6 +115,10 @@
 
   RecurseRoot(vals);
 
+  if (segv_page_count_ > 0) {
+    MEM_ALOGE("%zu pages skipped due to segfaults", segv_page_count_);
+  }
+
   return true;
 }
 
@@ -168,7 +174,15 @@
     handler.reset();
     return;
   }
-  MEM_ALOGW("failed to read page at %p, signal %d", si->si_addr, signal);
+  if (!segv_logged_) {
+    MEM_ALOGW("failed to read page at %p, signal %d", si->si_addr, signal);
+    if (walking_range_.begin != 0U) {
+      MEM_ALOGW("while walking range %p-%p", reinterpret_cast<void*>(walking_range_.begin),
+                reinterpret_cast<void*>(walking_range_.end));
+    }
+    segv_logged_ = true;
+  }
+  segv_page_count_++;
   if (!MapOverPage(si->si_addr)) {
     handler.reset();
   }

libmemunreachable/HeapWalker.h

diff --git a/libmemunreachable/HeapWalker.h b/libmemunreachable/HeapWalker.h
index 92a8325..b37cc62 100644
--- a/libmemunreachable/HeapWalker.h
+++ b/libmemunreachable/HeapWalker.h
@@ -53,7 +53,10 @@
         roots_(allocator),
         root_vals_(allocator),
         segv_handler_(),
-        walking_ptr_(0) {
+        walking_ptr_(0),
+        walking_range_{0, 0},
+        segv_logged_(false),
+        segv_page_count_(0) {
     valid_allocations_range_.end = 0;
     valid_allocations_range_.begin = ~valid_allocations_range_.end;
 
@@ -100,7 +103,10 @@
   allocator::vector<uintptr_t> root_vals_;
 
   ScopedSignalHandler segv_handler_;
-  uintptr_t walking_ptr_;
+  volatile uintptr_t walking_ptr_;
+  Range walking_range_;
+  bool segv_logged_;
+  size_t segv_page_count_;
 };
 
 template <class F>