ghc runtime by default (otherwise depending on a "configure" option) does memory allocation on their own by first mmapping a 1 TB range of memory into the process and then parceling out chunks from it. If one of the chunks is not needed, the kernel needs to be informed - otherwise the system would quickly run out of available RAM. ghc does that via madvise(2). There are two options when doing this informing: MADV_FREE - Means "I don't need this range or the data in it any more". Kernel promises to fail later accesses to it. MADV_DONTNEED - Means "I don't need this range right now - and I don't need the data in it anymore". Kernel promises to make later accesses to it succeed (if necessary by providing a new page initialized with zeroes). MADV_FREE was introduced in Linux 4.5. glibc 2.25 and later always define MADV_FREE. Unpatched ghc 8.0.2 will use either MADV_FREE or MADV_DONTNEED, determined at ghc compile time. Which of them will actually succeed is determined by the Linux kernel at run time. This patch makes ghc try MADV_FREE. If it doesn't work, it falls back to MADV_DONTNEED. The end result is that ghc programs free their memory with Linux < 4.5 again. See https://git.haskell.org/ghc.git/commitdiff/6576bf83cdf4eac05eb88a24aa934a736c91e3da for more information. --- a/rts/posix/OSMem.c +++ b/rts/posix/OSMem.c @@ -541,11 +541,24 @@ void osDecommitMemory(void *at, W_ size) #ifdef MADV_FREE // Try MADV_FREE first, FreeBSD has both and MADV_DONTNEED - // just swaps memory out + // just swaps memory out. Linux >= 4.5 has both DONTNEED and FREE; either + // will work as they both allow the system to free anonymous pages. + // It is important that we try both methods as the kernel which we were + // built on may differ from the kernel we are now running on. r = madvise(at, size, MADV_FREE); -#else - r = madvise(at, size, MADV_DONTNEED); + if(r < 0) { + if (errno == EINVAL) { + // Perhaps the system doesn't support MADV_FREE; fall-through and + // try MADV_DONTNEED. + } else { + sysErrorBelch("unable to decommit memory"); + } + } else { + return; + } #endif + + r = madvise(at, size, MADV_DONTNEED); if(r < 0) sysErrorBelch("unable to decommit memory"); } 67f623512a88ac20b879e00d442f85abe'>packages/aux-files/guile-launcher.c
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2020-10-05self: Use a 'guile' that doesn't complain about locales....Since commit ba48895899a117d6ace2209c3f54411a4a989133, selected UTF-8 locales are bundled. However, because 'guix-command' is itself a Guile script, users would still see Guile's warning, particularly on foreign distros: $ LC_ALL=sdf guix foo guile: warning: failed to install locale hint: Consider installing the `glibc-utf8-locales' [...] User commands would print that warning, but more importantly, each invocation of 'guix substitute' would print it, even though 'guix-daemon.service' explicitly chooses "en_US.utf8", which is in 'glibc-utf8-locales'. This leads to confusion since users would keep seeing this message unless/until they realize they also need to install 'glibc-utf8-locales' in root's profile. This patch gets rid of "guile: warning: ..." for a guix-pulled 'guix' command. * guix/self.scm (specification->package): Add "gcc-toolchain". (quiet-guile): New procedure. (guix-command): Use it. * gnu/packages/aux-files/guile-launcher.c: New file. * Makefile.am (AUX_FILES): Add it. Ludovic Courtès