public inbox for glibc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug malloc/18505] New: sysmalloc delete newly created heap
@ 2015-06-09 7:26 ma.jiang at zte dot com.cn
2015-06-10 13:26 ` [Bug malloc/18505] " fweimer at redhat dot com
0 siblings, 1 reply; 2+ messages in thread
From: ma.jiang at zte dot com.cn @ 2015-06-09 7:26 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=18505
Bug ID: 18505
Summary: sysmalloc delete newly created heap
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: malloc
Assignee: unassigned at sourceware dot org
Reporter: ma.jiang at zte dot com.cn
Target Milestone: ---
Hi all,
There is a bug in sysmalloc, which will slow down memory allocation.
In the "if ((heap = new_heap (nb + (MINSIZE + sizeof (*heap)),
mp_.top_pad)))" branch. " top (av) = chunk_at_offset (heap, sizeof (*heap));"
set the av->top to the newly created heap. Then "if (old_size >= MINSIZE)" we
will call " _int_free (av, old_top, 1);". _int_free will call heap_trim at the
end. In heap_trim, becasue "top_chunk == chunk_at_offset(heap, sizeof(*heap))"
is true(we just set av->top to the newly created heap...), the newly created
heap was deleted and topchunk was moved to oldtop.
Although we can probably get the memory from main_arena later(__libc_malloc
will retry if failed), this bug slow down allocation, and should be fixed.
In my opinion, _int_free should be called after the final allocation have
been done.Just add a new bool variable need_free_oldtop, replace all call to
_int_free with need_free_oldtop=true, add a line "if (need_free_oldtop)
_int_free(av, old_top, 1);" just before "return chunk2mem (p);". This should be
enough for the bug.
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug malloc/18505] sysmalloc delete newly created heap
2015-06-09 7:26 [Bug malloc/18505] New: sysmalloc delete newly created heap ma.jiang at zte dot com.cn
@ 2015-06-10 13:26 ` fweimer at redhat dot com
0 siblings, 0 replies; 2+ messages in thread
From: fweimer at redhat dot com @ 2015-06-10 13:26 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=18505
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |fweimer at redhat dot com
Flags| |security-
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2015-06-10 13:26 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-06-09 7:26 [Bug malloc/18505] New: sysmalloc delete newly created heap ma.jiang at zte dot com.cn
2015-06-10 13:26 ` [Bug malloc/18505] " fweimer at redhat dot com
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).