On Thu, Sep 30, 2021 at 11:10:10PM +0200, Vlastimil Babka wrote: > On 9/30/21 8:48 PM, Rustam Kovhaev wrote: > > On Thu, Sep 30, 2021 at 10:13:40AM +0200, Vlastimil Babka wrote: > >> > >> I think it's fair if something like XFS (not meant for tiny systems AFAIK?) > >> excludes SLOB (meant for tiny systems). Clearly nobody tried to use these > >> two together last 5 years anyway. > > > > +1 for adding Kconfig option, it seems like some things are not meant to > > be together. > > But if we patch SLOB, we won't need it. OK, so we consider XFS on SLOB a supported configuration that might be used and should be tested. I'll look into maybe adding a config with CONFIG_SLOB and CONFIG_XFS_FS to syzbot. It seems that we need to patch SLOB anyway, because any other code can hit the very same issue. > >> Maybe we could also just add the 4 bytes to all SLOB objects, declare > >> kfree() is always fine and be done with it. Yes, it will make SLOB footprint > >> somewhat less tiny, but even whan we added kmalloc power of two alignment > >> guarantees, the impact on SLOB was negligible. > > > > I'll send a patch to add a 4-byte header for kmem_cache_alloc() > > allocations. > > Thanks. Please report in the changelog slab usage from /proc/meminfo > before and after patch (at least a snapshot after a full boot). OK.
