Date: Tue, 23 Jan 2018 14:40:05 -0500 From: Pedro Giffuni <pfg@FreeBSD.org> To: cem@freebsd.org Cc: src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r328218 - in head/sys: amd64/amd64 arm/xscale/ixp425 arm64/arm64 cam cam/ctl compat/ndis dev/aacraid dev/advansys dev/ath dev/beri/virtio dev/bnxt dev/bwn dev/ciss dev/cxgbe/crypto dev/... Message-ID: <51ff8aef-5660-7857-e4d5-12cdc77bc071@FreeBSD.org> In-Reply-To: <CAG6CVpXxuFyHS11rF=NF6bSSkC2=xnDh=WnbK-aWp4sOomrZ7w@mail.gmail.com> References: <201801211542.w0LFgbsp005980@repo.freebsd.org> <CAG6CVpXxuFyHS11rF=NF6bSSkC2=xnDh=WnbK-aWp4sOomrZ7w@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi; On 23/01/2018 14:08, Conrad Meyer wrote: > Hi Pedro, > > On Sun, Jan 21, 2018 at 7:42 AM, Pedro F. Giffuni <pfg@freebsd.org> wrote: >> Author: pfg >> Date: Sun Jan 21 15:42:36 2018 >> New Revision: 328218 >> URL: https://svnweb.freebsd.org/changeset/base/328218 >> >> Log: >> Revert r327828, r327949, r327953, r328016-r328026, r328041: >> Uses of mallocarray(9). >> >> The use of mallocarray(9) has rocketed the required swap to build FreeBSD. >> This is likely caused by the allocation size attributes which put extra pressure >> on the compiler. > I'm confused about this change. Wouldn't it be better to remove the > annotation/attributes from mallocarray() than to remove the protection > against overflow? Not in my opinion: it would be better to detect such overflows at compile time (or through a static analyzer) than to have late notification though panics. The blind use of mallocarray(9) is probably a mistake also: we shouldn't use it unless there is some real risk of overflow. > (If the compiler is fixed in the future to not use > excessive memory with these attributes, they can be conditionalized on > compiler version, of course.) All in all, the compiler is not provably wrong: it's just using more swap space, which is rather inconvenient for small platforms but not necessarily wrong. Pedro.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?51ff8aef-5660-7857-e4d5-12cdc77bc071>