We should backport the following enhancements: commit c48d92b430c480de06762f80c104922239416826 Author: DJ Delorie <dj> Date: Thu Aug 8 19:09:43 2019 -0400 Add glibc.malloc.mxfast tunable * elf/dl-tunables.list: Add glibc.malloc.mxfast. * manual/tunables.texi: Document it. * malloc/malloc.c (do_set_mxfast): New. (__libc_mallopt): Call it. * malloc/arena.c: Add mxfast tunable. * malloc/tst-mxfast.c: New. * malloc/Makefile: Add it. Reviewed-by: Carlos O'Donell <carlos> commit f9769a239784772453d595bc2f4bed8739810e06 Author: Florian Weimer <fweimer> Date: Thu Aug 15 11:37:18 2019 +0200 malloc: Various cleanups for malloc/tst-mxfast We also need to fix the upstream bug, <https://sourceware.org/bugzilla/show_bug.cgi?id=24903>, or at least XFAIL the test (upstream and downstream). Currently, malloc/tst-mxfast fails on i686.
These commits also need to be backported in Fedora (30 and later at least).
This additional commit was needed in order to fix a bug in set_max_fast that caused a testsuite failure on i386: commit ff12e0fb91b9072800f031cb21fb2651ee7b6251 Author: DJ Delorie <dj> Date: Wed Oct 30 18:03:14 2019 -0400 Base max_fast on alignment, not width, of bins (Bug 24903) set_max_fast sets the "impossibly small" value based on, eventually, MALLOC_ALIGNMENT. The comparisons for the smallest chunk used is, eventually, MIN_CHUNK_SIZE. Note that i386 is the only platform where these are the same, so a smallest chunk *would* be put in a no-fastbins fastbin. This change calculates the "impossibly small" value based on MIN_CHUNK_SIZE instead, so that we can know it will always be impossibly small.
Verified with malloc/tst-mxfast
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2020:1828