* Re: selftests: cgroup: test_core - Unable to handle kernel NULL pointer dereference at virtual address [not found] ` <CA+G9fYsqrVTCd6yQtf=_xo_uGsMmaZNo3S2EJCERc07pwpxYAQ@mail.gmail.com> @ 2023-10-10 16:16 ` Roman Gushchin 2023-10-10 17:22 ` Shakeel Butt 0 siblings, 1 reply; 2+ messages in thread From: Roman Gushchin @ 2023-10-10 16:16 UTC (permalink / raw) To: Naresh Kamboju Cc: Andrew Morton, Johannes Weiner, Michal Hocko, Shakeel Butt, Muchun Song, linux-mm, Vlastimil Babka On Tue, Oct 10, 2023 at 12:23:06PM +0530, Naresh Kamboju wrote: > - mailing list. > [ my two cents ] > > Hi Roman, > > Thanks for fixing the reported issues. > > On Tue, 10 Oct 2023 at 03:13, Roman Gushchin <roman.gushchin@linux.dev> wrote: > > > > On Mon, Oct 09, 2023 at 04:08:13PM +0530, Naresh Kamboju wrote: > > > On Sun, 8 Oct 2023 at 21:09, Roman Gushchin <roman.gushchin@linux.dev> wrote: > > > > > > > > On Sun, Oct 08, 2023 at 11:30:52AM +0530, Naresh Kamboju wrote: > > > > > While running selftests: cgroup: test_kmem on FVP following kernel crash > > > > > noticed on Linux next 6.6.0-rc4-next-20231006. > > > > > > > > Hi Naresh! > > > > > > > > Thank you for the report! > > > > > > > > I've tried to reproduce it, but wasn't successful so far: I've run test_kmem > > > > for several hundred times and haven't seen the crash. > > > > > > If you look at the problematic test case is > > > selftests: cgroup: test_core > > > > Ah, got it, and immediately reproduced (and fixed). > > Thank you once again for all your effort! Hi Naresh! > Happy to test anytime. > In addition to that, I am happy to test any series of patches from lore > or your tree / branch. I posted v2 yesterday. > > > > > The problem happens because some kernel allocations happen after > > mem_cgroup_exit(), which was dropping the reference to task->objcg, > > but not zeroing the pointer, so it eventually caused a double-free. > > > > I gonna post an updated version of my patchset, which introduced the issue, > > with the fix merged (and some other minor changes). > > Would it be possible to add reported by tags in your patch series / fixes ? > > Reported-by: Linux Kernel Functional Testing <lkft@linaro.org> > Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> You totally deserve credits in the patchset, however reported-by tag will look strange in a non-fix commit (given that the fix is merged-in). This is a common scenario in mm where bugs are discovered and fixed in mm-unstable, so there are no separate fix commits. So I wonder if we need to introduce a new tag for this type of contribution. Andrew (and all other mm* maintainers), what do you think? Tested-by? Bugs-found-by? Stabilized-by? Thank you! ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: selftests: cgroup: test_core - Unable to handle kernel NULL pointer dereference at virtual address 2023-10-10 16:16 ` selftests: cgroup: test_core - Unable to handle kernel NULL pointer dereference at virtual address Roman Gushchin @ 2023-10-10 17:22 ` Shakeel Butt 0 siblings, 0 replies; 2+ messages in thread From: Shakeel Butt @ 2023-10-10 17:22 UTC (permalink / raw) To: Roman Gushchin Cc: Naresh Kamboju, Andrew Morton, Johannes Weiner, Michal Hocko, Muchun Song, linux-mm, Vlastimil Babka On Tue, Oct 10, 2023 at 9:16 AM Roman Gushchin <roman.gushchin@linux.dev> wrote: > > On Tue, Oct 10, 2023 at 12:23:06PM +0530, Naresh Kamboju wrote: > > - mailing list. > > [ my two cents ] > > > > Hi Roman, > > > > Thanks for fixing the reported issues. > > > > On Tue, 10 Oct 2023 at 03:13, Roman Gushchin <roman.gushchin@linux.dev> wrote: > > > > > > On Mon, Oct 09, 2023 at 04:08:13PM +0530, Naresh Kamboju wrote: > > > > On Sun, 8 Oct 2023 at 21:09, Roman Gushchin <roman.gushchin@linux.dev> wrote: > > > > > > > > > > On Sun, Oct 08, 2023 at 11:30:52AM +0530, Naresh Kamboju wrote: > > > > > > While running selftests: cgroup: test_kmem on FVP following kernel crash > > > > > > noticed on Linux next 6.6.0-rc4-next-20231006. > > > > > > > > > > Hi Naresh! > > > > > > > > > > Thank you for the report! > > > > > > > > > > I've tried to reproduce it, but wasn't successful so far: I've run test_kmem > > > > > for several hundred times and haven't seen the crash. > > > > > > > > If you look at the problematic test case is > > > > selftests: cgroup: test_core > > > > > > Ah, got it, and immediately reproduced (and fixed). > > > Thank you once again for all your effort! > > Hi Naresh! > > > Happy to test anytime. > > In addition to that, I am happy to test any series of patches from lore > > or your tree / branch. > > I posted v2 yesterday. > > > > > > > > > The problem happens because some kernel allocations happen after > > > mem_cgroup_exit(), which was dropping the reference to task->objcg, > > > but not zeroing the pointer, so it eventually caused a double-free. > > > > > > I gonna post an updated version of my patchset, which introduced the issue, > > > with the fix merged (and some other minor changes). > > > > > Would it be possible to add reported by tags in your patch series / fixes ? > > > > Reported-by: Linux Kernel Functional Testing <lkft@linaro.org> > > Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> > > You totally deserve credits in the patchset, however reported-by tag will look > strange in a non-fix commit (given that the fix is merged-in). > > This is a common scenario in mm where bugs are discovered and fixed in > mm-unstable, so there are no separate fix commits. So I wonder if we need to > introduce a new tag for this type of contribution. > > Andrew (and all other mm* maintainers), what do you think? > > Tested-by? > Bugs-found-by? > Stabilized-by? > "Tested-by:" seems reasonable. Is there some automation looking for "Reported-by:" for backports or contribution stats? ^ permalink raw reply [flat|nested] 2+ messages in thread
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2023-10-10 16:16 ` selftests: cgroup: test_core - Unable to handle kernel NULL pointer dereference at virtual address Roman Gushchin
2023-10-10 17:22 ` Shakeel Butt
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