kernel/linux.git/init, branch v5.5.13

int128: fix __uint128_t compiler test in Kconfig

2020-03-25T07:27:10+00:00

commit 3a7c733165a4799fa1beb262fe244bfbcdd1c163 upstream. The support for __uint128_t is dependent on the target bit size. GCC that defaults to the 32-bit can still build the 64-bit kernel with -m64 flag passed. However, $(cc-option,-D__SIZEOF_INT128__=0) is evaluated against the default machine bit, which may not match to the kernel it is building. Theoretically, this could be evaluated separately for 64BIT/32BIT. config CC_HAS_INT128 bool default !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) if 64BIT default !$(cc-option,$(m32-flag) -D__SIZEOF_INT128__=0) I simplified it more because the 32-bit compiler is unlikely to support __uint128_t. Fixes: c12d3362a74b ("int128: move __uint128_t compiler test to Kconfig") Reported-by: George Spelvin Signed-off-by: Masahiro Yamada Tested-by: George Spelvin Signed-off-by: Greg Kroah-Hartman

Revert "um: Enable CONFIG_CONSTRUCTORS"

2020-02-01T09:33:00+00:00

commit 87c9366e17259040a9118e06b6dc8de986e5d3d1 upstream. This reverts commit 786b2384bf1c ("um: Enable CONFIG_CONSTRUCTORS"). There are two issues with this commit, uncovered by Anton in tests on some (Debian) systems: 1) I completely forgot to call any constructors if CONFIG_CONSTRUCTORS isn't set. Don't recall now if it just wasn't needed on my system, or if I never tested this case. 2) With that fixed, it works - with CONFIG_CONSTRUCTORS *unset*. If I set CONFIG_CONSTRUCTORS, it fails again, which isn't totally unexpected since whatever wanted to run is likely to have to run before the kernel init etc. that calls the constructors in this case. Basically, some constructors that gcc emits (libc has?) need to run very early during init; the failure mode otherwise was that the ptrace fork test already failed: ---------------------- $ ./linux mem=512M Core dump limits : soft - 0 hard - NONE Checking that ptrace can change system call numbers...check_ptrace : child exited with exitcode 6, while expecting 0; status 0x67f Aborted ---------------------- Thinking more about this, it's clear that we simply cannot support CONFIG_CONSTRUCTORS in UML. All the cases we need now (gcov, kasan) involve not use of the __attribute__((constructor)), but instead some constructor code/entry generated by gcc. Therefore, we cannot distinguish between kernel constructors and system constructors. Thus, revert this commit. Cc: stable@vger.kernel.org [5.4+] Fixes: 786b2384bf1c ("um: Enable CONFIG_CONSTRUCTORS") Reported-by: Anton Ivanov Signed-off-by: Johannes Berg Acked-by: Anton Ivanov Signed-off-by: Greg Kroah-Hartman Signed-off-by: Richard Weinberger

mm, debug_pagealloc: don't rely on static keys too early

2020-01-14T02:19:02+00:00

Commit 96a2b03f281d ("mm, debug_pagelloc: use static keys to enable debugging") has introduced a static key to reduce overhead when debug_pagealloc is compiled in but not enabled. It relied on the assumption that jump_label_init() is called before parse_early_param() as in start_kernel(), so when the "debug_pagealloc=on" option is parsed, it is safe to enable the static key. However, it turns out multiple architectures call parse_early_param() earlier from their setup_arch(). x86 also calls jump_label_init() even earlier, so no issue was found while testing the commit, but same is not true for e.g. ppc64 and s390 where the kernel would not boot with debug_pagealloc=on as found by our QA. To fix this without tricky changes to init code of multiple architectures, this patch partially reverts the static key conversion from 96a2b03f281d. Init-time and non-fastpath calls (such as in arch code) of debug_pagealloc_enabled() will again test a simple bool variable. Fastpath mm code is converted to a new debug_pagealloc_enabled_static() variant that relies on the static key, which is enabled in a well-defined point in mm_init() where it's guaranteed that jump_label_init() has been called, regardless of architecture. [sfr@canb.auug.org.au: export _debug_pagealloc_enabled_early] Link: http://lkml.kernel.org/r/20200106164944.063ac07b@canb.auug.org.au Link: http://lkml.kernel.org/r/20191219130612.23171-1-vbabka@suse.cz Fixes: 96a2b03f281d ("mm, debug_pagelloc: use static keys to enable debugging") Signed-off-by: Vlastimil Babka Signed-off-by: Stephen Rothwell Cc: Joonsoo Kim Cc: "Kirill A. Shutemov" Cc: Michal Hocko Cc: Vlastimil Babka Cc: Matthew Wilcox Cc: Mel Gorman Cc: Peter Zijlstra Cc: Borislav Petkov Cc: Qian Cai Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Revert "fs: remove ksys_dup()"

2020-01-03T00:15:33+00:00

This reverts commit 8243186f0cc7 ("fs: remove ksys_dup()") and the subsequent fix for it in commit 2d3145f8d280 ("early init: fix error handling when opening /dev/console"). Trying to use filp_open() and f_dupfd() instead of pseudo-syscalls caused more trouble than what is worth it: it requires accessing vfs internals and it turns out there were other bugs in it too. In particular, the file reference counting was wrong - because unlike the original "open+2*dup" sequence it used "filp_open+3*f_dupfd" and thus had an extra leaked file reference. That in turn then caused odd problems with Androidx86 long after boot becaue of how the extra reference to the console kept the session active even after all file descriptors had been closed. Reported-by: youling 257 Cc: Arvind Sankar Cc: Al Viro Signed-off-by: Dominik Brodowski Signed-off-by: Linus Torvalds

early init: fix error handling when opening /dev/console

2019-12-17T21:10:11+00:00

The comment says "this should never fail", but it definitely can fail when you have odd initial boot filesystems, or kernel configurations. So get the error handling right: filp_open() returns an error pointer. Reported-by: Jesse Barnes Reported-by: youling 257 Fixes: 8243186f0cc7 ("fs: remove ksys_dup()") Cc: Dominik Brodowski Signed-off-by: Linus Torvalds

Fix root mounting with no mount options

2019-12-16T16:42:39+00:00

The "trivial conversion" in commit cccaa5e33525 ("init: use do_mount() instead of ksys_mount()") was totally broken, since it didn't handle the case of a NULL mount data pointer. And while I had "tested" it (and presumably Dominik had too) that bug was hidden by me having options. Cc: Dominik Brodowski Cc: Arnd Bergmann Reported-by: Ondřej Jirman Reported-by: Guenter Roeck Reported-by: Naresh Kamboju Reported-and-tested-by: Borislav Petkov Tested-by: Chris Clayton Tested-by: Eric Biggers Tested-by: Geert Uytterhoeven Tested-by: Guido Günther Signed-off-by: Linus Torvalds

fs: remove ksys_dup()

2019-12-12T18:00:36+00:00

ksys_dup() is used only at one place in the kernel, namely to duplicate fd 0 of /dev/console to stdout and stderr. The same functionality can be achieved by using functions already available within the kernel namespace. Signed-off-by: Dominik Brodowski

init: unify opening /dev/console as stdin/stdout/stderr

2019-12-12T17:58:24+00:00

Merge the two instances where /dev/console is opened as stdin/stdout/stderr. Signed-off-by: Dominik Brodowski

init: use do_mount() instead of ksys_mount()

2019-12-12T13:50:05+00:00

In prepare_namespace(), do_mount() can be used instead of ksys_mount() as the first and third argument are const strings in the kernel, the second and fourth argument are passed through anyway, and the fifth argument is NULL. In do_mount_root(), ksys_mount() is called with the first and third argument being already kernelspace strings, which do not need to be copied over from userspace to kernelspace (again). The second and fourth arguments are passed through to do_mount() anyway. The fifth argument, while already residing in kernelspace, needs to be put into a page of its own. Then, do_mount() can be used instead of ksys_mount(). Once this is done, there are no in-kernel users to ksys_mount() left, which can therefore be removed. Signed-off-by: Dominik Brodowski

initrd: use do_mount() instead of ksys_mount()

2019-12-12T13:50:03+00:00

All three calls to ksys_mount() in initrd-related kernel code can be switched over to do_mount(): - the first and third arguments are const strings in the kernel, and do not need to be copied over from userspace; - the fifth argument is NULL, and therefore no page needs to be, copied over from userspace; - the second and fourth argument are passed through anyway. Signed-off-by: Dominik Brodowski