bug#22691: 25.1.50; emacs memory usage blowing up

[Mark Oteiza]

from emacs -Q:

M-x eww RET fsf.org RET

CPU -> 100% and memory usage increases rapidly.

Looking at strace there is a massive stream of brk periodically
interspersed with:

03:47:03.331275 poll([{fd=6, events=POLLIN|POLLOUT}], 1, 4294967295) = 1 
([{fd=6, revents=POLLOUT}])
03:47:03.331317 writev(6, 
[{"\207\3\7\0\0\1\0\3\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\207\3\7\0"..., 
16380}, {NULL, 0}, {"", 0}], 3) = 16380
03:47:03.331374 recvmsg(6, 0x7ffed82aa0f0, 0) = -1 EAGAIN (Resource temporarily 
unavailable)

and

03:47:03.988437 faccessat(AT_FDCWD, 
"/usr/share/emacs/25.1.50/etc/images/close.xpm", R_OK) = 0
03:47:03.988595 faccessat(AT_FDCWD, 
"/usr/share/emacs/25.1.50/etc/images/refresh.xpm", R_OK) = 0
03:47:03.988706 faccessat(AT_FDCWD, 
"/usr/share/emacs/25.1.50/etc/images/left-arrow.xpm", R_OK) = 0
03:47:03.988814 faccessat(AT_FDCWD, 
"/usr/share/emacs/25.1.50/etc/images/right-arrow.xpm", R_OK) = 0
03:47:03.988921 faccessat(AT_FDCWD, 
"/usr/share/emacs/25.1.50/etc/images/show.xpm", R_OK) = 0

In the message buffer, a process filter error message:

 This Emacs mishandles this image file type

I seem to remember this message being added wrt cairo bugs. Could be
mistaken though.

In GNU Emacs 25.1.50.1 (x86_64-unknown-linux-gnu, X toolkit, cairo version 
1.14.6, Xaw scroll bars)
 of 2016-02-05 built on logos
Repository revision: 130056880fe9d807fbaee5bc5f68249ea9cf6438
Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --without-gconf --without-imagemagick --with-cairo
 --with-modules --with-x-toolkit=lucid 'CFLAGS=-march=x86-64
 -mtune=generic -O0 -pipe -fstack-protector-strong
 --param=ssp-buffer-size=4 -g -fvar-tracking-assignments -g
 -fvar-tracking-assignments'
 LDFLAGS=-Wl,-O0,--sort-common,--as-needed,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GSETTINGS NOTIFY ACL
GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
LUCID X11 MODULES

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix